Cheltenham Festival winner Ballyalton could return from injury over hurdles at Wetherby on Wednesday.
Winner of the novices' handicap chase at the big meeting in 2016, he subsequently finished fifth to Native River in the Grade One Mildmay Novices' Chase at Aintree.
It transpired he picked up a knock in that race which was enough to rule him out for the whole of last season.
"Ground permitting, Ballyalton will make his seasonal debut at Wetherby," said Williams.
"The horse is in good form and has had a good time since he came back into training in July.
"He is now ready to take a stepping stone to something like the BetVictor Gold Cup at Cheltenham next month.
"We are anxious to get a start into him and the hurdles' handicapper has been fair, which gives us the opportunity to go for a race like this."
"Seamour will run at Wetherby provided the ground is OK," said Ellison.
"He's been a bit disappointing this year on the Flat. He hasn't been showing the toe in his races that he had last year and we hope the switch back to hurdles will gee him up a bit and get his head back on the job.
"We will see how he goes, but I don't think we will stay hurdling if it doesn't look like he will be very useful. If he looks good, we will."