An investigation has been launched following the second "freak incident" at Epsom Downs Racecourse in four months, which threatened yesterday's Investec Spring Meeting.

Horse saddling boxes at the racecourse were blown onto Ashley Road, outside the racecourse, at 7.30am by winds, believed to be up to gale force.

Police had to be called in to direct the traffic caused by the road closure and staff at the racecourse battled to get the obstruction removed in time for the start of the races.

In January, high winds ripped off part of the roof of the £23.5m Duchess Stand causing serious disruption for days and huge embarrassment for the racecourse.

A report into the incident blamed "freak winds" and, with the Queen due to attend the Derby there in June at the start of her diamond jubilee celebrations, the managing director Rupert Trevelyan demanded a guarantee from contractors doing the repairs that it could never happen again.

Following yesterday's crisis the racecourse announced an immediate investigation into what had caused it.

A spokeswoman said yesterday: "Epsom Downs Racecourse has been affected by severe weather conditions today including gusty winds, rain and hail.

"Trained traffic stewards were immediately deployed to the area to manage the traffic past the obstruction and a team of Epsom Downs Racecourse staff began to dismantle the structure.

"The police were made aware of the situation and monitored the traffic management.

"The road was fully cleared before gates opened for racing at 12 noon."

Racing went ahead despite the weather, with the six-race card completed.

"In light of the continuing strong winds and as a precautionary safety measure horses were saddled in the stables before entering the parade ring," the spokeswoman added.

"A full investigation will now be undertaken to establish why this freak incident occurred.

"The racecourse apologises for any inconvenience caused to motorists this morning."

The continuation of yesterday’s racing, which marks the start of the racing season, was a big the relief of thousands of Epsom and Ewell residents who had taken up the offer of free tickets and braved the rain and winds to celebrate the borough's 75th anniversary.