Green’s Dictionary of Slang

a phr. used of anything that seems absolutely unlikely.

1959		T. Willis Woman in a Dressing Gown 92: Chance would be a fine thing.
1960		A. Burgess Doctor Is Sick (1972) 106: ‘I do smell like a pox-doctor’s clerk today.’ He sniffed elaborately at his left lapel. ‘Chance would be a fine thing, wouldn’t it?’.
1983		N. West Lucifer’s Brand 164: Chance would be a fine thing, Flair thought, but she didn't say so.
1988		J. McGown Stalking Horse 285: He had thought he would feel better. Maybe he really had hoped that Spencer would break down and confess, or slip up and give himself away. Chance would be a fine thing.
1993		I. Welsh Trainspotting 16: He didnae leave anything fir us, did he? Chance wid be a fine thing, the cunt.
1999		K. Sampson Powder 86: Chance would be a fine thing. I can’t get near them for trollops and drug dealers and yes-people.
2011		J. Chatwin Sister Celia 283: ’You are a wicked, wicked old man,’ she admonished him. ‘Chance would be a fine thing,’ retorted Eli.