Some observations
My mum is in the process of buying a static caravan for £10k on a well presented caravan park on the North Wales coast.
She is happy to make payment now and then go to sort out the paperwork, key transfer, etc after the safety checks are done by the sites caretaker.
I'd want paperwork and safety checks done prior to handing over cash.. you ask yourself the simple question, if the paper work throws up a problem (like all the additional ground rent/storage and other crazy high fees are revealed, or other non favourable terms in writing) or the safety checks highlight a problem then if you've already handed over your cash in what is effectively a sale with very little protection what motivation does the seller(s) have to address the problems?
The sale is being handled by the site owner as per the rules of the site.
Just google a bit and see the issue with site owners rules about them handling the sales.. it's absolutely rife with problems, crazy fees, them setting the selling price or what offers they will accept, etc..
She rings Barclays to make a bank transfer over the phone, gets put through to the fraud team
She should have gone in person to the branch.. she'd still get the third degree and they would be deeply suspicious but showing/proving identity in person is always easier.. over the phone? expect fraud departments to be on red-alert.
I transfered £15k to a reputable business for a motorbike in 2023 for a bike I had never even seen and was delivered to me no problem a week later. I was asked no questions.
You have much better protection in this scenario, and the key here is 'reputable business'.. the banks will know this and so happy to let it through.. My very elderly mother transferred £15k to the local VW Dealer with zero questions from the bank..
In contrast, I bought a car second hand and on picking up, I checked the car was still there, did my background checks on the seller, had the car inspected, and even was given the keys prior to going to the local branch of my bank to transfer the money, yet the branch made me jump through hoops, from double checking my identity (using my card/pin and showing other forms of ID) to going through 5 or 6 different 'scams' and even handed me a piece of paper with instructions on what to say if I was being coerced and could not talk openly.. It was annoying on one hand, but clearly its the level of scrutiny private transfers can attract..
The caravan site owner has never encountered anything like this she said.
Sure.. of course he hasn't.. the number of mis-sold and fraudulent scams going on these sites, the number of issues with 'site rules' over selling and he's never encountered anything like this before?
I'd calm down, and assuming you have done your research and have everything in writing about the caravan, fees, ground rents, selling rules and fees etc and still happy for your mum to proceed, then get her to go in to a branch with several forms of ID and they have no way to really stop you but will still question everything.