Royal travel costs have fallen by £600,000 to £3.9 million, but the expenditure on helicopter flights has topped £1 million, new accounts show.

A large number of trips were taken by helicopter, 179 journeys in total, during 2022-23, but their details are not listed as they fall below a £17,000 cost threshold.

The information was released in the Sovereign Grant annual report on royal finances for 2022-23, which listed major royal trips.

The most expensive was Charles and Camilla’s charter flight to Rwanda in June last year to attend a Commonwealth leaders’ summit, costing £186,571. The sum also paid for the King to travel to Aberdeen, from Brize Norton, after the trip and for a staff planning visit.

During a briefing for last year accounts a source said Charles is “pretty allergic” to travelling by helicopter and will always “raise an eyebrow” and object when the mode of transport is suggested.

The drop in travel costs for 2022-23 may in part be explained by a fall in the number of overseas trips.

A Buckingham Palace spokesman said: “We also saw a 43% decrease in business travel emissions, largely due to the reduced number of overseas visits requested by Government this year.”

Other major overseas trips included the King and Queen’s first state visit, which took them to Hamburg and Berlin in Germany by charter costing £146,219.

The Duke and Duchess of Edinburgh’s official Platinum Jubilee trip to St Lucia, St Vincent and Antigua, and a separate staff planning visit, cost £85,069.

The Prince and Princess of Wales’ scheduled airline flight, and a staff planning visit, to Boston in the US to attend the awards ceremony for William’s Earthshot Prize cost £48,034.

There were a number of residence to residence chartered flights made by Charles, one taken from Aberdeen to RAF Northolt last October cost £25,687, while another with Camilla, travelling from RAF Northolt to Aberdeen in September, cost £23,164.

The King used the royal train in January travelling from Ayr to Manchester to carry out a string of engagements at both locations over two days at a cost of £31,571.

Asked about the future of the royal train a Buckingham Palace spokesman said: “Once we determine what the future usage will be we’d be in a position to consider plans for a time table for decommissioning.”