I rented with this code in UK twice within last month

2 weeks rental from Luton airport, no questions asked, class C booked, car received Renault Capture disel manual, rate extremely cheap like 70 gbp per 14 days plus 12 gbp one way fee as returned at city station. At the invoice it says: rate 9J FINMECCANICA Non Discountable Rate, whatever that means

2 weeks rental from Milton Keynes city station, no questions asked, just manager was amused how good rate it is, class K booked, Audi A5 petrol automatic received, driving that great car now, again rate is crazy 115 gbp per 14 days

today i popped in at the station to add a second driver and same manager start asking questions like where i got that code, do i work for the company Leonardo/Finmechanica etc. Told her i used to work as a contractor, that is how i got the code but not doing a contract at the moment and not directly employed by them. Perhaps she was not convinced and told me i can continue with current rental and they honor the rate, but can't use that code for future bookings unless i have evidence i work for them. In a way i was asking for this as i got a great rate i should have stayed low and not showing to the branch again to get extra service.

to summarize you can get away with it but be prepared to prove affiliation with a company or have plan B reservation elsewhere.