I'm sure ringers out there can probably help identify the family that Alan's colour-ring came from. But all I can say is, it must be a large bird! I have a Gannet colour-ring in my hand (as you do), and that is only 3.3cm long. So an educated guess would be a goose, or even a swan? If Alan can narrow down the family, he has a fighting chance of finding the scheme here: http://www.cr-birding.org/.
