There had been 12 Brits in the top 300 at the end of January 2006 and there were 9 in the top 300 for most of the rest of 2006, often with a 10th player within a few places of getting in but not quite making it.
It may have happened since (I haven't got time to check thoroughly at the moment - I might if Liam does scrape in next Monday) but looking back at week 37 rankings over the last few years, it seems doubtful. In week 37 of each year that I've kept GB top 25 tables for (I did them before 2008 but they were overwritten each week instead of being saved), the GB men's no 10 was ranked (and the number of GB men in the top 500 was) ...