Read a bit today that surprised me. Monmouthshire used to be in England. It was 1974 that it changed. It was 23.55 can't remember the actual date, only one minute to debate and it was done, transferred to Wales. Not even recorded in Hansard. Also Newport at the same time.
Okay we only moved here 10 years ago so it was probably not reported in our local papers in L'Spa. Still very enlightening.
...and here is the Hansard entry of the 20th July 1972 which records the brief debate of that specific clause within the Bill which would become the Local Government Act 1972, two years ahead of the Act's commencement in 1974.