Carroll's agent, Richard Hale, said: "When John got banned at Royal Ascot last Wednesday we thought it would start on the Friday, nine days later. Then the paper said it was the Saturday and Sunday so we took that as right and he was booked to ride Colours For Gold.
"But he got a letter this morning saying the ban starts on Friday so he won't be able to ride, which is a shame as the filly has got a good chance."
Colours For Gold, who made a winning debut at Hamilton last month, is running in the Goffs pounds 100,000 Challenge, a race restricted to horses catalogued at the Goffs pounds 100,000 Challenge Sale last October.
Ed Dunlop announced yesterday that the top-weight, Jiyush, will miss Saturday's "Newcastle Brown Ale" Northumberland Plate. As a result, the weights for the pounds 100,000-added Newcastle contest will rise by a minimum of 6lb, with Lord Jim now set to head the handicap on 9st 10lb.
The four-year-old, quoted at 14-1 for the two-mile handicap by William Hill this morning, was seventh in the Gold Cup at Royal Ascot last week. His absence will enable Richard Quinn to ride the favourite, Windsor Castle, whose weight will rise to 8st 8lb.
Tote Credit offices on racecourses will no longer be allowed to offer board prices on meetings elsewhere. The decision was taken by the Horserace Betting Levy Board at their monthly meeting in London. The Board made the move after, last month, confirming its policy of approving betting in on-course betting offices only at starting price.