OP - you had the ability to say "No, you are not searching my bag." At which point they would have been able to say "Then you are not coming into this cinema." And you would have got your money back for your ticket, gone on your merry way, and this issue would not have arisen.
The cinema did not hustle you away into a tiny bamboo cell, strip you naked and beat you with thistles while firing a water cannon at you. They told you that they needed to search your bag, and presumably, when you had the chance to say "Okay then, here it is" or "No chance, stuff your movie" you took the former option.
I'm still struggling to understand why you think any lawyer can help you here. You may have found it embarrassing (it can be embarrassing being groped as you go into a concert hall or a football stadium, especially if you've got a hard-on) but you allowed them to do it when you had the chance to say no. And you were caught out - you were trying to take a drink purchased elsewhere into the cinema, when there were signs telling you that you couldn't do this. Maybe Cineworld should be asking if there is a lawyer in the house, seeing as you were blatantly flouting the rules.
All this waffle about "Well, they've never done it before" doesn't wash. Who says they have to have done it before? And how do you know they haven't done it before? Do you actually live in the cinema, and spend your whole life watching each and every staff member to make sure that they've never done it before? And, how do you know that they didn't recognise you from the last time you went in and blatantly drank your own drink, even though that wasn't allowed? How do you know that you're not a marked man, and you will be searched everytime you go anywhere from now on, cos Cineworld have posted your face up and down the country? Cos you're the one who's broke the rules!
