This is a very good example of the type, certainly one of the best examples of the 55 recorded here. It's particularly unusual to see so much of the reverse, with just about the full horse as well as the kite and some of the spiral decoration below. Obverse isn't quite so good, but that's quite common for this type, which was often struck with quite a worn obverse die.
The kite staters probably date from the late first century BC, perhaps between about 20 - 0 BC. They're very often struck in base gold, very few have been analyzed, but they seem to have about 30% gold, 20% silver or a little less, and as much as 50% or a bit more copper. So the red gold colour is not surprising.
This kite stater type is listed in Van Arsdell's 'Celtic Coinage of Britain' as VA 825-1, and Spink's 'Coins of England' as no. 392.
