The champion jockey had been expected to delay his decision until after he had tested the going by riding over the course today, but has instead cast a firm vote for Captain Dibble. That is an action likely to be mirrored by punters and the the eight-year-old, on whom Scudamore won last year's Scottish National, may be favourite when the field lines up on Saturday.
The move leaves David Bridgwater, who had been standing by for Captain Dibble, without a ride and means that Pipe will have an even more difficult task in trying to find partners for his mammoth entry.
Unlikely to receive a call from Pipe are any of the female riders qualified for the race. Female jockeys continue to find it hard to make an impact and, with scant opportunities, their greatest moment in National Hunt's greatest spectacular is likely to remain the celluloid one when Mickey Rooney was doing the saddling up.
The distaff riding representative on Saturday is Judy Davies, who will partner Formula One for John Edwards. Davies, 22, is the first woman to ride in the National since Tarnya Davis pulled up on Numerate in 1989, and although her horse is a 200-1 shot she will not carry a sense of awe along with her saddle into the parade ring.
'I'm not riding just to make up the numbers, I'm out to win,' said Davies, whose mount was beaten just two lengths by Royal Athlete three seasons ago. 'I expect him to run well if he can recapture his form of a few years ago. I've been riding him this morning and he seems in good form.
'I walked Aintree a few times over the years, but I'll arrive early tomorrow to have another look. It holds no particular terrors for me. The fences are no worse than Haydock Park.'
Davies gets her eye in over the obstacles today when she partners Solar Cloud in the John Hughes Memorial Trophy. At the weekend, she may find as many as three stablemates from Edwards's Ross-on-Wye yard lining up with her as the trainer attempts to win his first National. The closest he has come to success was when Sandy Sprite and Ron Barry landed in front over the final fence in 1971, but broke down on the run-in, eventually finishing fifth to Specify.
Peter Niven, the leading northern jockey, was booked for one of the Edwards horses, the 100-1 chance Direct, yesterday. It will be a third National ride for the Scotsman, who pulled up on Hotplate in 1991 and finished 14th on Rubika 12 months ago.
With the weather deteriorating, the going at Aintree is expected to be close to perfect on Saturday. The going was not so good for the first wave of Irish horses which arrived at the course yesterday. High winds had prevented their boat from sailing and the four Irish runners arrived 10 hours late at 5am.
GRAND NATIONAL (Saturday, Aintree): Coral: 7-1 Royal Athlete, 8-1 Captain Dibble & Zeta's Lad, 9-1 Romany King, 10-1 Party Politics, 14-1 others.
Zafonic, the ante-post favourite for the 2,000 Guineas, is one of six declarations for the Prix Djebel at Maisons- Laffitte next Wednesday.