Debbie
Thanks very much for your helpful comments. I match 36/37 with my contact. My surname, Mellanby, goes back at least to the mid-1600s in the Teesside area. The Allen name is also around in that area and there is even an Allen/Mellanby marriage, showing that the families were known to each other. My matches, two cousins, live in the US and have no knowledge of any English ancestry so it would be nice to firm up on the circumstantial evidence that their origins may lie in NE England. I will give serious thought to setting up a geographical project.
Yes, I have had the deep clade tests done and have no mutations downstream of that defining Haplogroup I2. I have been in touch with the Rootsweb discussion groups but at present I feel I need to learn a lot more about the whole subject of DNA before perhaps getting involved with Haplogroup projects. I am broadly familiar with FTDNA and ISOGG and will have a look at the other sites you mention.
I really appreciate your help.
John