I would really recommend Marlborough Horseboxes. They are based in Lancs and were really helpful when i bought my 3.5t box from them 3 years ago. Ive got a Marlborough Hunter, but they do various models and chassis' to choose from to suit your requirements. Ive been so pleased with mine, its economical, easy to drive , brilliant to keep clean and the horses love it.
Me too ! Ive ordered a Marlborough Cob (in between a Hunter and a Sport) and it should be ready in two weeks. Cant wait. The service I have had so far has been excellent. I think you are quite near me so if you want to have a look at it when it arrives you are welcome.