In Mikhail Kasyanov's 19th-floor office in a southern Moscow block, a brass telescope is trained on the Kremlin's distant domes. It may be as close as he gets.

Mr Kasyanov was once an insider - finance minister under Boris Yeltsin, and then Vladimir Putin's prime minister until being fired in February 2004 in what was seen partly as retribution for criticising the treatment of Mikhail Khodorkovsky, the jailed former oil billionaire.