Balmoral, Scotland - "Heheheh, gonna thrash The Darkies!" the old curmudgeon was heard muttering as the Palace's Aintgottaprayer.con sporting account accepted the wager last night.
A tip-off about England star batsman Alistair Cook breaking Test records saw HRH dig deep into the Missus' Scottish sinking fund for a wee cricketing flutter on the England side chances.
By teatime Cook's tally had reached a mind blowing 294 as wild Edgbaston crowds saluted the extraordinary Third Test hero.
The Old Duke, watching in his Balmoral Castle eyrie, reportedly nearly fell out of his G-Plan Rocker as Raina caught Cook at six short of the magic 300 - a score only ever achieved by five other England batsmen.
England skipper Andrew Strauss then declared at 710-7 as India went in for their second innings.
Bettingwise, it's left the field wide open for Philip's wager to still come good when England begin their own second innings.
"Man's a genius, I tell you, a bloody genius!" the Duke rambled before dropping orf into his pint-sized balloon of 1927 Creme de Menthe.
At odds of 50-1 the old bastard stands to make £50,000 should Cook prevail.
Betting closes at midnight tonight.