Luke Heighton, opendemocracy.net, A Jihadist census: ‘Al Qaeda-Affiliated and ‘Homegrown’ Jihadism in the UK: 1999-2010' 5 Oct 2010
See Jytte Klausen, Institute for Strategic Dialogue, ‘Al Qaeda-Affiliated and ‘Homegrown’ Jihadism in the UK: 1999-2010'
The PDF report can be downloaded from this page. I haven't read this report yet (but have added it to my reading list!).