The parliament of Northern Ireland also used STV for the same (er, well, inverted) reasons from 1921 until the Unionist majority forced a change to FPTP for most seats in 1929.

More generally, STV was the default choice for assemblies throughout the British Empire (and became known as 'the British system' as a result) from the late 19th century onwards.

It was even agreed on for use in Westminster in 1919 - though only the university seats ever actually used it - making it "more traditional" than the current single-member FPTP system which dates only from 1949. The failure to actually implement it was part of a more general reactionary movement in the aftermath of the war, when Lloyd George's promise of a "land fit for heroes" was thoroughly betrayed.

The Irish system seems to work well, and can be used as a comparator for considering what the UK might look like if that betrayal hadn't happened.