The easiest answer would be 47712 last October (I think).
If you mean in BR service, then I can't answer definitively unfortunately, but the relevant Rail Express formations article states that push-pull working came to an end on May 12th 1990. Looking at the Class 47 archives page for that month (
https://class47archives.blogspot.com/2014_01_04_archive.html#May), the last Edinburgh - Glasgow working I can find before then, where the loco would be at the rear if the formation was the right way round, is 47711 working the 16:00 Edinburgh - Glasgow on Wednesday 9th May.
There were some 47/7s on passenger workings in Scotland after that date but it is increasingly likely that they would have been conventionally hauled.