Hmmm… I wonder how reliable these are…

They’re billed as “extrapolations”, which is not encouraging. Still, for what they’re worth, here they are:

Sex
6,407,580 people in the UK
2,320,200 are male
2,789,540 are female

Age
3,241,800 men between 18 and 25
1,565,520 women between 18 and 25
907,620 men between 25 and 35
1,006,420 women between 25 and 35
227,220 men and women between 35 and 60

Professional vs student
5,160,740 who are not students
295,260 are in High School
447,820 are in college
503,760 Alumni

Damien Mulley’s done the same thing for Irish users of Facebook.

Thanks to Rory Cellan-Jones for the original link.