Thanks Lawrence,
Oh dear - the amended circuit below should be correct and just to make sure that it is, I've bodged it together in true 'bodgertronics' fashion, so not only have technical standards fallen today here at Bleak House - practical standards have nose-dived too. Having satisfied myself that it works, it's been consigned to the bin. (First time in a long time that I've made anything that hasn't been on a purpose made PCB, housed in a bespoke comb-jointed mahogany box!). The transistors were NOS germanium PNP AC166s, which must have been at least 50 years old. One had an HFE of 130 - the other, 134, so quite closely matched. As with the original 'ESTON' the waveform isn't a square wave, and I had to increase the value of the two caps to 100nF to get the frequency down below 2kHz. As can be seen, it's 1.943 kHz.
Normal service will be resumed as soon as possible.
