Thanks for all the tips and advice, ive been having a play over the last few days with different set ups generally the same rolling stock but different locos and weight configs.....
My Hornby A4 Gadwall is reasonable however slips with 4 coaches (Hornby Pullmans) ive liberated a weight from an old lima class 37 which I fixed to the top of the boiler with white tac for testing purposes with this setup I can get to 5 coaches. My Hornby tornado pulls better but again slips on 5, the TTS duke of Gloucester struggles to pull 3 coaches and this one isn't slipping its stalling not sure if I can up the power to the motor as it seems severely underpowered.
Given the incline is on my mainline ive had no choice but to alter the gradient so went to a 1:40 which is much better all round my gadwall and tornado can pull 9 with a little weight for traction, the Duke does 4 before running out of steam (must be a loco issue).
So my next question does anyone recommend weights which I could fix to the inside of the boiler?
With regard the duke any thoughts would be appreciated.