Cecil rekindled the glory years in 2007 with his best season for some time, including saddling Light Shift to an emotional success in the Oaks in June.
His Twice Over emerged as a candidate for Classic honours this term when taking two back-end events at Newmarket in good style.
And a backer at Coral’s Mayfair branch in London has plunked down £12,000 in cash on the Khalid Abdullah-owned Observatory colt to give Cecil a fifth win in the blue riband after Slip Anchor, Reference Point, Commander In Chief and Oath.
The customer also placed a £2,000 ante-post treble on Twice Over at 12-1 in the Derby, Kauto Star at 5-4 for the Gold Cup and Sublimity at 4-1 in the Champion Hurdle.
Coral reacted to the sizeable wager by cutting Twice Over to 8-1 from 12-1 for the Epsom Classic.
Spokesman Simon Clare said: “The customer has placed a handful of bets before in this Coral branch, but nothing of this magnitude.
“We already had substantial liabilities on Twice Over for the Derby and this massive bet has forced us to slash his price and run for cover.”
Epsom Derby, Coral bet: 7-2 New Approach, 8-1 Twice Over, 16-1 Thewayyouare, 20-1 Confront, 25-1 Washington Irving, 33-1 bar.