Thanks guys. It all seems double dutch on Maplins. There are AC adaptors but it is not clear to me what they connect to or are intended for.
Spaceman, picture of the beast:
The details on the adaptor are:
D-Tech
Display technology co Ltd
AC/DC Adaptor
Model name: DTA-XGA02
Input rating: 100-240Vac, 50/60 Hz, 0.8A
Output rating: 12Vdc 3A
There's a diagram that looks like a scale from (-) to (+) with a semi circle in the middle like a capital C and an O inside it.
The mains connection socket on the adaptor is a 3 pin affair shaped like the club on a pack of cards. The box itself is 110mm x 50mm approx and the piece that plugs into the monitor is 5mm diameter.
Hope that helps!