Green’s Dictionary of Slang

(UK prison) gruel.

1890		Sporting Times 8 Nov. 1/5: The Staff of the Sporting Times on a Car Representing a Visit to Shifter [...] in Holloway Castle. Banner of Toke. Banner of Streamy. Banner of Duff. Banner of Spotted Baby. Banner of Thick. Banner of two Doorsteps [...] Banner of Oh Don’t it Niff.
1892		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’.