The KX series of telephone boxes in the United Kingdom was introduced by BT (British Telecom) in 1985. Following the privatisation of BT in 1984, the company decided to create a newly designed and improved take on the British telephone box, which at this point consisted of predominantly red telephone boxes which BT had recently acquired, the most common being the iconic K6 box. These red boxes were considered flawed in parts by BT for several reasons, including cost, lack of ventilation, accessibility and maintenance. After a series of trials and an earlier aborted project, BT announced they were to spend £160m on a series of new phoneboxes, new computer chip controlled payphones and the phasing out of all older red telephone boxes. The KX Kiosk range was designed for BT by Warwick based David Carter Associates DCA_Design - at the time 'DCA Design International', but were engineered by GKN in Telford.
The main model of the KX range is the square upright rectangular KX100 kiosk with or without a door. Upon launch, there were two further production models - the open pedestal 'KX200' and the triangular 'KX300'. The housings were initially produced at a rate of 5,000-6,000 a year between 1985-1986, with production intensifying to around 3,000 a month between 1987-1989 before slowing down in the early-to-mid-1990s once the older kiosk estate was replaced and the number of public payphones had more than doubled. In 1987, the smaller 'vandal resistant' KX410 and KX420 pillars joined the range (but both were built by smaller companies than GKN with low production numbers). In 1990, the indoor KX500 pillar/wall range was designed, having several sub-variants, and production of the KX200 and KX300 dropped off. In 1996, the KX100 was adapted into a 'new' upgraded model called the KX+.
At the peak of BT's public telephone network's popularity in 1999 the company operated around 140,000 payphones. The figure includes phones housed in the red heritage models from the GPO and Post Office era, within/on the KX range (including thousands of the pillar and wall mounted KX500 series which could host between 1-4 payphones on one unit). Exact numbers of KX housings produced are not known but research is underway and likely to be announced in a forthcoming book about the KX housings in late 2026. New production of KX kiosks and housings largely ceased in 2001, with BT contracting GKN to refurbish recovered models for re-use. From 2002, BT began a programme of identifying and removing thousands of underused payphones and the redundant housings. By 2024, BT's own figures placed the remaining payphone estate at just 15,000 and the company intends to reduce the number to somewhere between 2,500 and 5,000 kiosks with working payphones by 2027.
Whilst the updated functionality of the KX housings were praised, the designs were criticised by the Design and Architecture establishment as utilitarian; functionality over form; and stylistically inferior to the red telephone boxes. Critics missed the point that in order to make the payphone service profitable and more robust against the constant idle and criminal vandalism BT had asked specifically for housing that cost less to maintain; did not require repainting every two-years; could be accessed by disabled users, children and the elderly (the old GPO kiosks had very heavy doors), and did away with the need for 72 panes of glass, having between 0, 3, and 6 depending on KX model. The plan to replace the red boxes was heavily criticised from a heritage perspective, and this led to a successful public campaign by the c20th Society (at the time called 'The Thirties Society' to save many of the red kiosks. The c20th Society later ran campaigns to secure the listing of the K8 models in the late 2000's and in 2024, campaigned for the listing of a handful of KX models for their important contribution to public telecommunications - and indeed, because the arrival of the KX models caused the initial campaign to list the older red GPO kiosks.
Most of the main KX series had their branding livery revamped after BT changed their corporate logo in 1991. Occasionally old branding resurface on elevations hidden for decades when one of a pair of kiosks is removed. Production of the KX100/200/300 range stopped in 1996 when the KX+ was launched, attempting to address the criticisms that the original KX100 had received by lowering the door handle, brightening the interior and enlarging the upper windows. The biggest revision was the addition of a red roof dome - reminiscent of older phone boxes. Later versions of the KX+ incorporated broadband connection and blue domes. BT was reported to have stopped making enclosed telephone boxes altogether in 2001. From 2007 BT Payphones continued to be installed in modified KX100/KX+ that had been converted to ATM cash-dispensers. From 2007 BT started to introduce the semi-open JCDecaux advert pillar called the ST6 (Street Talk 6). Later advertising pillars followed, with side mounted keypad public phones, then digital touchscreens.
Background In 1980, preparing for privatisation, Post Office Telephones, who owned all of the United Kingdom's telephone boxes, except those in Hull, was renamed British Telecom, later to become simply BT. The most common telephone box in the United Kingdom was the K6 red telephone box, introduced in 1935. The newly formed BT inherited a 1979 project to design new kiosks for the 1980s, but costs were escalating and it would come to nothing. There were many local kiosk ideas trialed on a regional basis by regional telephone boards of first Post Office Telecomm's, then BT. Other projects in included the introduction of phonecard-operated telephone kiosks in July 1981 after a successful trial, with the phones in the kiosks being named Cardphones. Another project, this time localised in the BT NorthWest Region over winter 1980/81, was a trial painting of about 80 red telephone boxes (mostly K6 but some K8's) in yellow, as a test of BT's 'new' corporate colour. It was only ever a trial, but the National press misquoted a BT press release and erroneously told the public every red phonebox (77,000 of them) would become yellow. This was harshly received by the public, with the Daily Mail launching a campaign "against the yellow peril" and questions were asked in Parliament. In the House of Lords, the Earl of Gowrie, the Minister of State for Employment, called on BT "to abandon this ridiculous scheme". In the House of Commons, Mark Lennox-Boyd MP asked the then Prime Minister, Margaret Thatcher, if she would treat the decision "with the greatest possible dismay". Thatcher, who herself was responsible for the privatisation, would only say that she could "see my honourable Friend's point".
The Daily Mail claimed its campaigning had worked yet BT once again made it clear it had only ever been a trial, largely ignored by national media until 4 examples were painted in London to trial four different shades of yellow. BT explained it had "been an experiment" and that no final decision had been reached. Nonetheless, whilst they had sympathised with what the public saw as a cultural icon, BT then turned their attention to what customer research had established were embedded flaws in all of Britain's cast iron telephone boxes. They considered them 'outdated and no longer meeting the needs of the public, finding that few people like using them, and noted their expensive cost, difficult maintenance and how they could not be used by handicapped people' . Furthermore, the red phoneboxes were noted for a lack of ventilation and little space. Although British Telecom had begun introducing the yellow vandal proof '7A "Oakham" booth' in 1981 to several locations with limited floor space or extreme vandalism, it was with their imminent privatisation in 1984, that forced BT back to the drawing board. The result, announced publicly in early 1985 was a range of new telephone boxes, called the KX, which improved on the previous telephone boxes and addressed their concerns.
Launch In early 1985, British Telecom announced a £160 million modernisation scheme for the public telephone network inherited from the General Post Office. Described as "a major improvement to the public telephone service", the "new designs that were to be the most perfect telephone kiosks you could imagine." They were both BT's first standardised telephone booths and their first altogether, having only been privatised less than half a year earlier. The new telephone boxes were named the KX series. Whilst it is unknown what the initials stand for, it is believed the "K" stands for kiosk, following the Post Office telephone box naming system.
The introduction of the new kiosks was also to see the eventual replacement of all existing prior telephone boxes. In January 1985, Nick Kane, the Director of Marketing for BT Local Communications Services, announced the replacement plan and stated they were being replaced because they "no longer meet the needs of our customers. Few people like to use them. They are expensive and difficult to clean and maintain and cannot be used by handicapped people".
The first KX type to be installed, a KX100, was unveiled in Leicester Square, London though this was not the first installation location of the type. BT later stated the KX models "were cheaper to maintain, more resistant to vandalism and were designed to blend in with any surroundings. Special attention was paid to environmental considerations, acoustics, weather protection, lighting and ventilation after intensive market research was conducted into customers' needs. The designs assisted customers with disabilities and allowed access to wheelchair users."
The KX series was not the first attempt to replace the red telephone box with regards to easier access, lower maintenance and brighter lighting, as they follow Post Office Telephone's "Croydon" telephone boxes from the 1970's. The Croydon kiosks were experimental housings built by Post Office Telecoms London (South) around 1975 to replace the ageing red kiosks. They were designed in Croydon, Surrey and trialled locally in that area. The exact date is not known but there is speculation that they may date from 1972. The Croydon kiosks were initially unpainted stainless steel, but by 1982, BT London was painting them black with a bright yellow roof and a phone handset silhouette (instead of the word 'Telephone'). Open pedestal versions and door-free Croydons were built and whilst the trials were successful, the cost of the materials and assembly made it too expensive for BT to mass produce. The design was used nationally as a stop gap between 1983-1986 while the KX range was developed but untimately the Croydons were mostly removed from sites by 1988. Regardless, the design of the Croydon boxes proved an important influence on the KX100 and others in the KX range. It was also described as looking "quite stunning" and as influencing the Australian Telstra telephone boxes.
Original models The original KX telephone booths were designed by DCA (David Carter Associates) and re-engineered by GKN after an initial batch of pre production models from America proved flimsy. They are of light-weight construction using stainless steel struts affixed to a stainless steel rear panel and roof, into which anodised aluminum components formed frames around glass/acrylic windows. They were also fitted with sound proofing back boards and featured a windswept gap at the base to prevent litter from accumulating, and "better lighting." As had recently been retrofitted to several existing red telephone boxes, many of the coin-operated KX telephone boxes used the BT Payphone 600.