WOW alasdair, your comment about Bedford is kinda blunt. I happen to know the man and he isn't over in Moscow because he's stupid. He's actually fairly sharp when it comes to R/C. I think the OP mentioned the CG has been checked and as combatpigg mentioned wing vs stab incidence angles can and do play a big part in pitch control.

We should be able to help the OP with his problem without resorting to degrading each others input.