Cazza, does yours have a "Webb" mark as part of the design? If not, it could just as easily be Richardson.
As for "values" of these, 15 years ago, they could be bought at UK fairs for around £200-300, but for some reason they gained in interest and £600 was sometimes asked. I saw one at that high price and as soon as I was seen looking at it, the dealer immediately offered it to me for £300. I did not buy it.
I do, however, have an example marked "Webb" which is not so tall, has a wide rim and has what I think is Tulip decoration.