Relocating staff to a single central London site cost magic circle firm Allen & Overy almost £25m, it has emerged. The full cost of the move was revealed in its LLP annual report and financial statements for 2010/11.

The one-off outlays meant that continuing costs rose by 6% to £675m and profit before taxation remained broadly flat at £431m.

The number of lawyers employed during the year rose from 2,092 to 2,152, contributing to a £20m rise in staff costs to £326m. Profit per full partner was unchanged at £11m.

The firm moved into four floors of a Canary Wharf skyscraper in 2003 on a reported 25-year lease, but cancelled that arrangement in 2010 to move around 200 staff into its existing Bishops Square headquarters.

The financial report notes that the decision reduced duplicated costs and dedicated transport between the two sites. But vacating the property in mid-lease incurred a one-off charge to cover rent while the office is empty: for a year, that would be £3.4m.

The decision to relocate some administrative support services from London to Belfast, announced in February 2011, involved costs of £4m, including a provision of £3m for redundancies over 12 months.