A cabinet used to hold the ‘letters patent’ for granting Douglas city status cost the council £13,318 plus VAT.
The documents are on display in the city hall and were given to the council by Queen Camilla on behalf of King Charles.
Previously it was revealed that the local authority spent £5,000 on her visit in March and wasn’t given any financial support from the government.
An earlier display cabinet for the documents was £390.