Green’s Dictionary of Slang

an ‘amateur night’ at the local public house.

1877		J. Greenwood Dick Temple I 219: ‘What is a blinko, for instance?’ ‘Well, it’s a kind of entertainment, singing and that,’ replied the old fellow, ‘to which strangers are not invited – least of all the police.’.
1883		Daily Tel. 4 Aug. 2/1: An Harmonic blinko, the proceeds of which will be given towards buying a barrow for Young Duckling, who has got married with no visible means of support [F&H].