Mike:

Welcome to the wacky world of old phones.

The easiest way to adapt the phone is to install a short length of 25-pair key system cable, equipped with a connector that will mate with the plug on your phone.

This will allow you to find the Tip & Ring leads (or A & B as they are called in your country) for the first (or any) of the line keys.

Does the plug on your phone look like the male plug in this photo?

[Linked Image from blackbox.com]

Cables with one female connector and a stub end are available cheaply here in the states. If you do a search in Ebay you'll find them, or one of us can ship you one.

This method will allow you to place and receive calls, but the lamps under the buttons will not work, nor will the HOLD feature. To get all that working, you'll need a Key Service Unit (KSU) and one or more Key Telephone Units (KTU). All this stuff is available over here...not sure over where you are. There are members of several antique telephone collecting clubs in the UK and in Europe. They can be of help, too.

Arthur P. Bloom
"30 years of faithful service...15 years on hold"