I believe it’s just a letter of consent, which is the norm for any lease company, the other forms of id are required are described here, from Halfords, lots of companies do them from tee shirt printers to graphics companies, but if it has to be an official one then it’s the norm to show the followering.
https://www.halfords.com/advice/motoring/service/replacement-number-plates-made-at-halfords