Well I went to see Graham Williams. I'd been introduced to Graham by Derek Goodwin, and I saw the blue prints for K9. K9 hadn't then been built, and there was this sort of Scottie tartan collar round [his neck]. I said, 'Well do you want him Scottish?' and he said, 'Oh no, heaven forfend, we don't want Scottish,' so I said, 'What do you want?'

He said, 'Well really K9 is the receptory and the deliverer of all information. He's an absolute know-all, but we want his voice to sound as if it comes out of a tiny little elliptical speaker in a cheap radio.'

So I put a few voices down on a tape and then I had panic calls from the BBC to say, 'Have you accepted the job?' I assumed there was a queue yards long to play K9, I wasn't to know, so I said, 'Yes, yes, fine, I didn't know it was just me they wanted.'

I just put up [my voice] a few levels, clipped it as much as possible, made it sound like a machine. It couldn't sound like a dog, because K9 isn't a dog, but I made it sound as mechanical as possible.

Is it true that it was originally electronically treated and you gradually moved over to doing the whole thing yourself?

Yes. Dick Mills was in charge of sound effects and all the rest then, and he put the voice through a ring modulator or whatever gizmos he'd got at the time to make it sound a little more electronic. But here I am today recording this and I'm in the studio with all the others on a clean mic. It's extraordinary, the actor's found a way of doing it for himself.