Larry is the latest in a long line of official mousers at Downing Street, including stalwart ratter Humphrey, who served under Margaret Thatcher and John Major but was retired in 1997, shortly after Tony Blair's arrival. Humphrey was succeeded for a short period in 2007 by Sybil, the pet of then chancellor Alistair Darling, but the renowned mouser failed to settle and returned to Scotland.