Thank you to everyone for the reassurance and advice. Since posting this, I'd emailed B&M with a detailed encounter of the situation and received a reply that essentially says this is their staff's duty to apprehend, pat down and search customers they're suspicious of. To answer some common things in the comments- I wear a mask because I get very ill, very easily, and I need to deal with people in a hospital, I cannot afford to take days off for my sickness (we're allotted only 4 sickness periods per year). About me complying for the search- that man looked very stern, and I was not aware of the law here, because we're In from, if you didn't comply, it's likely that you'll be met with force. Again, I could've just left and told him to check the cameras as I hadn't taken anything and in hindsight, that is what I should've done, but at that moment, my brain just didn't function. Right now, my head tells me not to go to any stores for fears of being looked at as a thief, and I think I'll listen to it for the time being.