Net migration to Britain last year hit a record high, according to official figures published Thursday.The Office for National Statistics said that net migration in 2010 was 252, 000, the highest calendar year figure on record. The ONS said that while immigration was steady at 591,000, the rise in the net figure was due to a fall in the number of people leaving the country.In all, 339,000 people emigrated from the UK, the lowest level of emigration since 2001. Emigration by non-British citizens also fell to 203,000 from a peak of 255,000 in 2008.The ONS said fewer people were leaving the country from the UK for work-related reasons.Provisional figures for the 12 months to March 2011 show 174,000 left due to work, the lowest figure for five years.The main reason for immigration into the UK continued to be to study - which rose from 211,000 in 2009 to 238,000 last year.