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 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.  So many were returned that the company made a huge loss and would have been bankrupted but for a government subsidy.  

The watch had to be disassembled to change the battery, the display was off as a default, two buttons could be pressed, then the time could be read as long as the button was pressed down, this unfortunately drained the battery very quickly indeed.

The watch had to be disassembled to change the battery, the display was off as a default, two buttons could be pressed, then the time could be read as long as the button was pressed down, this unfortunately drained the battery very quickly indeed.

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

Our Black Watch comes in its original display case.