The Wakefield-based firm, which was set up 64 years ago, will fulfil the contract for plumbed-in coolers at Buckingham Gate, the Duchy of
Cornwall's London base, through its Thirsty 4 Water service.
Simon Wilkes, head of Thirsty 4 Water, said: "We are assured
that our branding and charitable connections have played an important part in assisting us to win this contract.
"It is a great success for our company and I am thrilled we are able to include the Duchy of Cornwall in our growing list of customers."
The firm has also won business recently with Tower
Bridge, in London, and the Liverpool set of Channel 4 soap Hollyoaks.
If it completes five years of service to the Duchy of Cornwall it can apply for a Royal Warrant of Appointment
Mr Wilkes added: "Just because we are based in Yorkshire,
it doesn't mean we can't compete and win against the big boys down south.
"Overheads and rates are much more affordable in the north, which helps
us to keep costs down for both ourselves and our customers."
Wilkes Group's Catering Supplies business also provides products ranging from disposable cups, plates and plastic cutlery to food
containers, sandwich packaging and disposable glassware.