The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.
Letter from Karen Dunnell, dated April 2009:
As National Statistician, I have been asked to respond to your question concerning how many Somali citizens are currently resident in the United Kingdom. (269752)
The Office for National Statistics collects data on nationality from the Annual Population Survey, which is the Labour Force Survey (LFS) plus various sample boosts, which covers residents of the UK. The latest estimates available are for the 12 month period of July 2007 to June 2008, these show that the estimated number of UK residents with Somalian nationality was 71,000. The margin of error around this estimate is +/- 11,000. It should be noted that the LFS:-
excludes students in halls who do not have a UK resident parent
excludes people in most other types of communal establishments (e.g. hotels, boarding houses, hostels, mobile home sites, etc)
is grossed to population estimates of those living in private households that only include migrants staying for 12 months or more.