Old style Jack, 1960's?

[gusto]

Hi all,
I recently picked up this guitar (see link) as I just liked the look of it, obviously I normally go for basses and ignore the 6 string monsters that turn you into the beast known as a lead guitar player......... Anyway.

It is currently with Robbie at RIM Basses getting some well needed TLC. Robbie has told me that the jack input is the very old (metric/pre-metric?) size jack ant that the leads we all use now are the wrong size. Anyone know where I can get my hands on the correct size cable so I can plug this baby in to my amp without having to butcher the input on the guitar?
Any help or more info on this guitar greatly appreciated, especially a valuation.

Link to pics:
[url="http://basschat.co.uk/index.php?showtopic=94901"]http://basschat.co.uk/index.php?showtopic=94901[/url]

[Ou7shined]

Just fit a 1/4" jack and keep the original in case you want to sell it on again.

[BigRedX]

Is it [url="http://www.bryant-broadcast.co.uk/BD%209300"]PO316/Bantam type jack[/url]?