The Black Watch was launched in September 1975 by Sinclair Radionics, later Sinclair Research, the company behind the ZX81 and ZX Spectrum. It cost £24.95 ready-built or £17.95 as a kit. It had a red LED display and was powered by two hearing aid batteries.

The watch was marketed by the company as follows: 'if that [the technical description] sounds technical, think of the outcome: a watch with no moving parts, a watch with nothing to go wrong, a watch which gives accuracy never achievable by the most precise mechanical engineering.'

The Black Watch, however, was riddled with problems. The display was off as a default, and only displayed the time when the hidden button was pressed. This drained the battery very quickly, despite Sinclair's claims that it would last for a year. The watch and its ITT chip were susceptible to static which resulted in the display freezing on one very bright digit, causing the batteries to drain and become very hot, until the point that they apparently sometimes exploded.

So many were returned that the company made a huge loss and would have been bankrupted were it not for the National Enterprise Board who stepped in and injected money into the company.

However, the watch is a good early example of Sinclair's interest in aesthetically pleasing electronic products. 

These five watches were donated by Chris Wilding formerly of Sinclair Radionics and Sinclair Electronics. They are a development model that was developed to display the date, as well as the time.