the phone box mystery

Life is full of little mysteries and unanswered questions, questions like 'why do men have nipples?', 'why do we hiccup?', 'why does drinking tea always make me desperately need the toilet?', and 'why are there random video cassettes in my local phone box?'.

Yes, video cassettes.
Each time I walk past the phone box on the way to the local shop there are a selection of videos balanced in different places in the cubicle.
Phil and I have been puzzling over this for a while. The videos are usually in boxes but sometimes just have stickers on them. They are always 'innocent' (or at least marked as such) - things like 'Watch with Mother' or 'Snow White and the Seven Dwarfs' or 'Pride and Prejudice'.

The weirdest part though is the fact that they are changed regularly. The first time we noticed the cassettes we assumed they had just been left there as a one off. Sure enough the next time we walked past they had gone and the cubicle was empty - we assumed that someone had simply thrown them away, however, on our next trip past the phone box there were more videos - and they were different.
We don't walk past all that often, but each time we do there seems to be a new selection available, always seemingly of an innocent nature just like the first crop.

We don't have a TV or VCR and so haven't picked any of them up to find out what is actually on them, and to be honest I'm not really sure I want to know anyway...

Several theories have been discussed - is this the base of a porn exchange ring? Are these stolen CCTV tapes? Or have we stumbled upon something even more sinister?

One thing is for sure - I really don't get it!