Nerdy techy question about dictation machines

[frogs]

For reasons too long and tedious to go into, I have in front of me a Philips dictation machine and minicassette, the contents of which I need to load into my computer.

Unfortunately the headphone socket of the dictaphone is too small to take a standard minijack (ie. headphone pluggy thing). Does anyone happen to know what the connector/jack is called that I need to make this machine talk to me, and (ideally) where I can get it from?

Thanks! I think I have just worked out that it's a 2.5mm to 3.5 mm adaptor, where 3.5 mm is the normal jack size and 2.5 mm is the irritating nonstandard size some dictaphones use. If I'm v. v. lucky, a spotty teenager in Currys will know what I'm talking about...