Unfortunately I don't recognise that model, and unless I know what each of the wiring terminals does, I can't help you. The wire colours don't help either as they would have been chosen by the original installers personal preferences. It may well follow the same format as the newer models, but it's risky to assume that.
I'm assuming you don't have the instructions for it, and the best way to find out what each wire does, would by testing them with a multimeter but I can't do that on a forum. (unless you have a multimeter and can use it) Is there not a wiring diagram inside the lid? or a legend somewhere saying what each terminal is for? Failing that, if you could post a photo of the front of the cover, someone might recognise it.
Having said that, if you can't find anything else and you can do the following safely, here is something that you can try. Start with the heating cold so that the boiler will fire up when asked.
1. Remove the blue wire from terminal 4 and insulate it safely. With the heating set to be 'on' so that turning the Danfoss up and down would normally operate the boiler, try it. does it still operate it now? When completed, put the blue wire back in terminal 4
2. Remove the two black wires from terminal 1, and reconnect them together away from the thermostat. With the heating set to be 'on' so that turning the Danfoss up and down would normally fire up the boiler, try it. does it still operate the boiler now? When completed, put the two black wires back in terminal 1
3. Remove the brown wire from terminal 2 and insulate it safely. With the heating set to be 'on' so that turning the Danfoss up and down would normally fire up the boiler, try it. does it still operate the boiler now? When completed, put the brown wire back in terminal 2
I would expect that in two of the above tests, that the heating won't operate and in one that it will.