Unlike Henley or Ascot, it is not one of the traditional events of the Season, but the day a group of cheeky Perth youngsters took a dip in an aristocrat's swimming pool will live on in their memories for many summers to come.

The 12 boys enjoyed an afternoon splash in the Earl of Mansfield's private pool within the grounds of Scone Palace.

However, their forbidden fun came to an end after 20 minutes when they were spotted and chased off by two palace employees.

The youngsters, all from the North Muirton housing estate in Perth, made off with a life ring, a beach ball and a 7ft-long inflatable crocodile.

Yesterday, one of the Earl's uninvited guests, Mark Donaldson, 17, said: ''We swam across the River Tay and walked about a quarter of a mile up to the palace. No one saw us go into the garden.

''Then we opened the plastic dome over the swimming pool and dived in. There were about 12 of us went into the pool. We messed around with the inflatables.

''After about 20 minutes we came out because it was really hot. We went around the front of the palace to ask if it was okay to use the pool but there was no one around.''

He added: ''We went back in the pool and that's when we got caught. These two men came over and shouted 'get out of there'. We made a run for it with the crocodile. It was difficult to carry because it was so big.''

The swimming pool is at the front of the palace in the Earl's private garden, which is sealed off from the public.

Mark Donaldson, Daniel Whyte, 15, and Scott Lamond, 14, who all swam in the Earl's pool on Sunday afternoon were back swimming in the Tay yesterday within full view of the palace.

Mark joked: ''We were thinking about going back there today but we don't want to push our luck.

''Lady Mansfield is okay. There was one time she invited some people who had fallen into the river into the palace and warmed them up with cups of tea. I don't think we should upset her.

''We can't return their crocodile because we left it on the river bank last night and when we came back today it had gone.''

The boys refused to name their nine accomplices in the cheeky swimming session.

Ms Helen Walch, the administrator in charge at the palace, said: ''I know it was a hot holiday weekend I just cannot believe the cheek of them.

''They ran around the palace grounds dripping wet and took an inflatable crocodile with them.

''The police were called but it will be up to the Earl whether to take any further action about the things that were taken. He is abroad on holiday just now.''

The Earl of Mansfield is one of Scotland's richest men with a 27,000-acre estate and a 125-room home. He has campaigned for the Stone of Destiny to be returned to Scone Palace where it was kept for nearly 500 years before it was taken by King Edward I in 1296.

A palace insider said: ''The Earl will be upset that the boys were in his private pool. He doesn't even allow his staff to swim in it, so he won't be happy when he finds out what has happened.''

A spokesman for Tayside Police confirmed that officers attended the palace on Sunday afternoon but he did not anticipate any further action. He added: ''We will be keeping a watchful eye on the Scone Palace grounds for the next few days.''