An Australian flagpole was partially cut and a memorial and information plaque were sprayed with blue paint at a Harefield churchyard, in Middlesex, the main grave site for Australian soldiers in the United Kingdom.

The UK High Commissioner Alexander Downer said people should continue with their plans for Anzac Day regardless of the attack.

"While we are not sure of the motivation of this vandalism the report is very disappointing," Mr Downer told AAP in a statement.

He said there were 45 commemorative events taking place across the UK.

The Commonwealth War Graves Commission has meticulously restored the 112 headstones in preparation for the centenary, but it is believed none of these were attacked.

"The vandalism is very upsetting for the commission after all the work that has taken place over the last three months," a commission spokesman said in a statement.

A spokesman told the ABC it would either cut through the pole, lowering the height of the flag or support the pole with brackets, but the centenary would go ahead.

"It will be safe and usable for the ceremony," the spokesman said.

The story of how the soldiers and one nurse came to be buried at Harefield stems from a wealthy Australian couple, Charles and Letitia Billyard-Leake who lived in Britain during the war. They offered the use of Harefield House and its grounds to Australia's defence department in November 1914.

It became a home for convalescing soldiers of the Australian Imperial Force at first, but expanded to become a 1000-bed auxiliary hospital with additional huts built to take the wounded soldiers. It was originally thought it might hold 50 soldiers in winter and 150 during the spring and summer.

In all, the auxilliary hospital treated 50,000 patients with 112 dying, including one Australian nurse Ruby Dickinson. These were buried in the cemetery.

On Anzac Day, local villagers gather in the nearby 12th century church to pay tribute to the soldiers and children lay fresh flowers on the graves.

- with APP