REVISED arrangements for the Royal wedding caused an unprecedented headache for racing last night.

Grand National officials decided to delay one of the sport's favourite events to ensure maximum television coverage.

The decision caused a knock-on effect, with the British Horseracing Board announcing three other courses had moved races planned for Saturday afternoon to give prominence to the famous steeplechase at Aintree.

The Grand National will be pushed back 25 minutes because its coverage clashed with Prince Charles' wedding, which was switched from Friday to Saturday because it coincided with the Pope's funeral in Rome.

The National traditionally begins at 3.45pm but will now be run at 4.10pm.

Charles and Camilla are expected to emerge from Windsor Castle's St George's Chapel at about 3.15pm after their blessing, which starts at 2.30pm.

The BBC's coverage will carry on until 3.30pm, which would have overlapped with the build-up to the Grand National.

At 3.30pm, BBC1 will go live to Aintree to cover the race.

Charles Barnett, managing director at Aintree, said: ''We have made this decision in consultation with the BBC in order to offer members of the public the best possible afternoon's viewing.''

Ladbrokes called the change unprecedented, but predicted that more people would have a bet on the Nationl, increasing the bookies' turnover.

The 4.20pm at Lingfield is being delayed until 4.30pm, Hereford moves the 4.10pm chase to 4pm and Newcastle brings forward the Haggerston Castle Maiden Stakes from 4.10pm to 3.50pm.

* Two intruders broke into the private area of Windsor Castle, days before the royal wedding, Scotland Yard said last night.

An internal Windsor inquiry is being carried out into the intrusion, which happened earlier this week