Beaulieu Road is the classic in my area.
It has seen an hourly Sunday service since at least 1997.
However, I don't think it's ever had an hourly service during this period Mon-Sat, even though for much of the time it could have been done easily. There is an hourly "stopping" service over the line but for some unbeknown reason the stop is skipped alternate hours, even though the stop could be added without messing up the path.
In some years during this period there was no stopper over this section of line at all, the Poole fast stopped at Ashurst, and Beaulieu Road had almost no off-peak service at all - so it has been even worse!
Can't remember when the hourly Mon-Sat service ended, but it was still present in the September 1991 timetable and had alnost certainly been present before that since the electrification in 1967. Probably sometime in the 1992/93 period which was notable for cuts on the "South Western" before things started improving from around 1995 onwards - but not for Beaulieu Road.
Granted it's a quiet station but at this time of the year in particular, and on Saturdays for around half the year, it sees decent use from New Forest visitors - so could do with an hourly service.
Another case of the "pointless omission of a stop" often seen nowadays (see also XC and the next-door station, Brockenhurst).