[2] When it became clear that Radionics was failing, Sinclair took steps to ensure that he would be able to continue to pursue his commercial goals.

In February 1975, he changed the name of Ablesdeal Ltd (a shelf company he had bought in September 1973 for just such an eventuality) to Westminster Mail Order Ltd.

The Sinclair Cambridge was launched in 1973 as a basic calculator and later in several enhanced versions supporting memory, advanced mathematical functions, and programmability.

The Sinclair Scientific featuring trigonometric and logarithmic functions and employing Reverse Polish Notation was introduced in 1974.

In May 1979, Jim Westwood, Sinclair's chief engineer, designed a new microcomputer based on the Zilog Z80 microprocessor.

In March 1982 Sinclair Research Ltd made an £8.55m profit on turnover of £27.17m, including a £383,000 government grant to develop a flat screen.

In 1982 Clive Sinclair converted the Barker & Wadsworth mineral water bottling factory at 25 Willis Road, Cambridge, into the company's new headquarters.

In January 1983 the ZX Spectrum personal computer was presented at the Las Vegas Consumer Electronics Show.

[citation needed] The Sinclair QL was announced on 12 January 1984, shortly before the Apple Macintosh went on sale.

Fully working QLs were not available until late summer and complaints against Sinclair regarding delays were upheld by the Advertising Standards Authority in May of that year.

However, the machine did not sell as well as expected and, because retailers still had unsold stock, Sinclair's income from orders dipped alarmingly in January.

An enhanced model, the ZX Spectrum 128, was launched in Spain in September 1985, with development funded by the Spanish distributor Investronica.

Sinclair Research had reportedly intended a public offering of shares on 12 March 1985, but this offering was postponed, ostensibly due to turmoil in the microcomputer industry, with Acorn Computers undergoing refinancing, and other companies such as Sinclair's competitor Oric and distributor Prism entering receivership.

In June 1985, business magnate Robert Maxwell announced a takeover of Sinclair Research, through Hollis Brothers, a subsidiary of his Pergamon Press.

In 1992, the "Zike" electric bicycle was released, Sinclair's second attempt at changing people's means of transport.

In November 2010, Sinclair Research announced the X-1 two-wheel electric vehicle, which failed to reach production.

[16] A digital multimeter with an LED display, measuring voltage (DC and AC), current and resistance, released in 1975.

Production was delayed by several months, due to unfinished development of hardware and software at the time of the QL's launch.

[18] Hardware reliability problems and software bugs resulted in the QL acquiring a poor reputation from which it never recovered.

The ZX Spectrum 128, with RAM expanded to 128 kB, a sound chip and other enhancements, was launched in Spain in September 1985 and the UK in January 1986, priced at £179.95.

[19] The following computer products were under development at Sinclair Research during the 1980s but never reached production: Standing for "Low Cost Colour Computer", the LC3 was developed during 1983 by Martin Brennan and was intended to be a cheap Z80-based games console implemented in two chips, using ROM and (non-volatile) RAM cartridges for storage.

[20][21][22] This project was intended to create a greatly enhanced ZX Spectrum, possibly rivalling the Commodore Amiga.

Loki was to have a 7 MHz Z80H CPU, 128 KiB of RAM, and two custom chips providing much enhanced graphics and audio capabilities.

Among the features associated with Tyche were increased RAM capacity, internal floppy disk drives, the Psion Xchange application suite on ROM, and possibly the GEM GUI.

[26] In November 2010 Sinclair told The Guardian newspaper that he was working on a new prototype electric vehicle, called the X-1, to be launched within a year.