In reply to andybevan57:
Salewa mini dream II
Excellent harness and widely adjustable. First bought it for my son when he was 5, still wearing it age 9 and it will last another year or two easily.
I combine it with a chest harness made from a 120cm sling (two overhand knots to the ends to make rope loops, then looped into a figure of 8). Much better and comfortabe than full body harnesses (except for glacier tours) because of the padded leg loops.
CB