Thanks for the input folks. It appears that there may be something a bit different with my circuit board, no matter, I will figure it out the old fashioned way! I will let you know what I find out.

To rich and johnathon, Thanks for your interest so far.
The make of decoder is irrelavant, but they (a 5 pack) were supplied a few weeks ago by a local supplier. I am using a Lenz system with a LH 100 controller. The decoder is an 8 pin job and is inserted the right way round.  Surprisingly, I deliberately inserted it a about k but all that happened was nothing. I did check where the wheel pick up wires ended up and they were going to the correct place on the decoder.
It looks a bit like I will have to work out the circuit board the long way. I  was just being lazy!

Hi Folks, I have just fitted a decoder (non sound) to a 2-6-6-2 loco and while I have forward and reverse I have no lights.  Is there a wiring diagram for the 2 circuit boards avalable to enable me to check out what is meant to do what?  I am reluctent to rewire the the thng as the existing circuit boards look well made. If I have to do it I will but would prefer not to.  It goes without saying that the decoder was properly checked out before installing in the tender and all the connections are good between the loco and the tender.
Pete