My SM dog Friday pulls alot which makes her scratch even more. Although I always thought a step-in would be best for her I've decided to put her in the style of harness Karlin was talking about. Another one is a Gentle Leader and I don't know if you can get them in England or not.
I make harnesses myself and I'm making hers in ultra-suede so at least it's soft were it hits her on her chest. When I first starting trying to design a harness that would minimize her scratching this is the style I made with the ring on the top of her like a step-in but she still pulled so now I'm putting the ring in front which is making her pull less and scratch less!
I know other cavalier and pet owners who had success with this style!
Terri, mom to Monday, Wednesday, Friday and Sunday