King of the road: Prince Charles tries a Harley Davidson on for size

Try this on for size: The Prince of Wales hops on the impressive bike during his meeting to promote London Poppy Day

During the meeting, a biker sent a message to Prince Charles - via a very rude badge on his jacket that he hoped he'd notice.

The unknown man, from the Royal British Legion Riders Branch, was dressed in a leather waistcoat covered in badges, and had the not-so-subtle message sewn onto the back of it.

It is not known if the Prince noticed it, but it read: 'F*** off I don't like you'.

The Prince of Wales shook hands with the bikers as he was meeting Poppy Appeal volunteers and celebrity supporters.

Subtle: The man had the message - highlighted above with expletive obscured by MailOnline - sewn into the back of his waistcoat and it appeared Prince Charles didn't notice

Charles greeted those working to raise money on board the London Poppy Day red bus at Clarence House as part of the campaign to raise £1million in a single day from donations across the capital.

TV presenter and Poppy Day ambassador Ben Shephard said Charles spent some time joking and laughing when he boarded the Routemaster.

'We thought we could try and drive off with him on the bus and launch a ransom to raise more money,' Mr Shephard said.

'But he thought we wouldn’t get very far.'

Charles also joked about having a sing-along on the bus and riding a Harley Davidson.

On board: Charles joked about having a sing-along on the bus and looked at home on a Harley Davidson

The Prince then met volunteers inside Clarence House’s Poppy Day counting room, where the money raised is rapidly counted in machines.

Hundreds of volunteers have the important job of tallying the funds at five counting stations across London including, for the first time, the one at Clarence House.

Richard Atkinson, a banker and volunteer counter at Clarence House, said Charles wanted to know how the money counting machines worked.

All aboard: Prince Charles poses for a picture on red London bus taken over by the Royal British Legion for the campaign

'He was very intrigued and tried to understand the logistics of how this final part of the process works,' Mr Atkinson said.

'He was also very interested to know what we all did as day jobs as well.'

This year the volunteers, representing the Army, Navy, RAF and a host of companies, aim to raise £1 million in a single day across the capital, more than twice what was raised on London Poppy Day 2011.

The countdown to £1 million will take place in Covent Garden where an electronic totaliser will update the amount raised.

During the Poppy Appeal, the Royal British Legion is aiming to raise £42 million - £2 million more than last year’s record £40 million - to carry out vital work, including providing immediate support and life-long care to armed forces families in need.

Other Poppy Day events began today at Covent Garden piazza with the arrival of the London Poppy Day Routemaster, which will tour the capital throughout the day.