selby newcomer:
at Costco in Lutterworth, they have a bar that comes round the trailer wheel as you reverse on the bay, it locks into position when the loading ramp is in place, so you couldn’t move even if you wanted too. they still take your keys off you though
And the amount of times this bar jams, the clerk has a scaffold pole in the gatehouse and has it out a fair few times a day, firs time I went in as a new driver it caught me and I twisted the rear doors as I forced it 
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