Did you know, the first computer to be used in a business was built and operated in Kaevener House at Hammersmith Road in West London, although it wasn’t quite a desktop PC.
The British LEO I (Lyons Electronic Office I) computer started operations in 1951 long a useful transistor was invented and well before the microprocessor was even considered. Exactly what the computer did is a little unclear, but most likely the computer would process information such as payroll.
Running at a blistering 500 kHz, the computer was capable of receiving multiple inputs and outputs although it was admittedly missing a mouse or a monitor, but could receive “high speed” paper tape readers and punches taking 100 instructions a minute (quite a bit quicker than your average typist).
The computer was most likely dismantled and the old Cadby Hall was demolished, but some British LEO III’s were still running in British Telecom until 1981, and you’re probably reading on a machine legacy of the LEO.
More details about the LEO on Wikipedia.