There most certainly is.
Its been stated many times that even if a film is passed by the BBFC this does not make it immune from the Obscene Publications Act
This would usually only cover the R18 category these days but in the 80's the OPA was used to ban plenty of films so its your imagination thats out of step aswell
Even the BBFC's certificated and cut version of The Evil Dead was successfully banned by one court in the 80's (and today we have the full uncut version )
A Clockwork Orange had a BBFC certificate but was banned by its director and was only released in the UK after he died.
Films with BBFC certificates that were banned for home consumption in the UK until the 90's or 00's include Death Wish,The Exorcist,The Texas Chainsaw Massacre (although that only screened in London),Straw Dogs and others.
Murder Set Pieces appears to have been banned too despite the BBFC only viewing the version cut by 12 minutes.