Green’s Dictionary of Slang

whipping adj.

[fig. use of whip v.1 (2b)]

excellent, first-rate.

[UK]Sporting Times 9 Apr. 1/3: Voice of gentleman describing himself as a Toke and Streamy Merchant [...] ‘Bill, d’you know the [House of] Detention skilly? Aw’fly rich in flour [...] oh, it’s wipping!’.