That was a true classic cinema.
I found this interesting image of how movies were advertised in the 1930's, this is the same Empire cinema Great Yarmouth - advertising a 1935 film - Sanders of the river.
For value of this window card, I think it would have more general appeal rather than movie poster collectors as it has strong 60's graphics and doesn't mention a particular movie but does mention a classic cinema.
Many 60's 'venue' adverts have been reproduced, especially for rock\pop, but this looks OK. Hard to put a price on it as I would not buy it personally so it is a matter of taste. If you like it, think it is genuine, and are looking at around 20 pounds, I don't see any issues.
