Michael Jackson, his owner, said: 'We have run out of options. He won't be turned away in a field because I don't think you should do that, so he will be kept in training and will make public appearances if anyone wants him.'
Morley Street has been one of the leading jumpers of recent years, winning the Breeders' Cup Chase at Belmont Park and Fair Hill, Maryland.
After establishing his credentials as a top bumper horse in 1988, Morley Street had a fine novice hurdling season in 1989, although defeated in the Sun Alliance Hurdle at Cheltenham. The following year he ran in the Champion Hurdle for the first time, finishing fifth to Kribensis.
After success in that race in 1991, he was subsequently sixth to Royal Gait in the 1992 running and 12th to Granville Again, his full-brother, in 1993.
His most memorable win came the next month when he won the Aintree Hurdle for the fourth consecutive year, swooping late under a fine ride from Graham Bradley.
Morley Street's role as a chaser was interrupted when he started breaking blood vessels, an affliction which blighted his later career. But he was also a fine performer on the Flat, running Great Marquess to a short-head in the 1991 Doncaster Cup.