Ainslie said conditions were difficult in Russia

No-one else in the history of the single-hander class has won four world titles, let alone four consecutively.

The Briton's latest triumph came in Moscow where he won three of the eight races and had three second places.

The delighted Olympic champion said: "It's the toughest venue I've ever sailed at for a major event, so this win is the best yet. It means a lot."

Since it was first contested in the 1950s, only four men have won the title three times.

Only one, Brazil's Joerg Bruder, took three in a row, but he was killed in a plane crash in 1973 on his way to defend his crown.

Since moving into the class in 2002, Ainslie has won every world championship and every European title except one - when was hampered by a virus but still came second.

He is hoping to compete in the Finn class at the Beijing Olympics in 2008 but is also part of the Team New Zealand crew for the 2007 America's Cup.