[baldrick]

Our bedroom has two lights fed from 1 switch, a primary light in the actual room and a secondary light in the 'lobby'. Currently I have a GET 400W 2 way dimmer and the secondary light is a fitting with a 60W SES candle bulb.

We want to replace the primary light with a very nice fitting but it is 6 x 12v 20w bulbs. From the looks of it the fixture used a magnet based transformer so what sort of dimmer do I need to control both lights?

Most low voltage dimmers will also control mains as well but beware of so-called 'Universal' dimmers which will probably not work with the wire wound transformer. Varilight do a low-voltage / dual purpose dimmer that should be suitable (Their IQP range)

[Bruce_]

Check if the GET dimmer is suitable for inductive loads. Magnetic transformer = inductive load. If not, you could swap to an electronic transformer, but make sure it is dimmable.

Otherwise, you could just give it a try. If you're happy to risk the dimmer failing if it doesn't work, that is.