It doesn't happen much now, but if breakdowns dictated it, i'd work until finished although i always got paid , indeed used to get bonus's for it.
Ive seen me (does that make sense ?) start at 6am, finish at 7pm, just get home, knife and fork in hand...phone rings

...breakdown. Back to work, replace an electric motor on a machine that took me till 3am the following morning. That is rare, but the responsibility comes with the job, so i'm ok with it.
An old friends just packed in her job. Office based, always working through lunch, then 'expected' to work an extra hour or two...unpaid. F'kem...i simply wouldnt do it. Outrageous.