Is football fan a German prince or a brazen imposter?

The strange case of the FA Cup tie and the Kaiser

Maidenhead in Berkshire is no stranger to excitement, and on Tuesday it was gearing up for another night of high-society celebrations. The local football club, celebrating its 140th anniversary, was marking the occasion with a visit from its royal patron, His Royal Highness Prince Frederick von Saxe-Lauenberg.

Enter the Prince, who arrived at the stadium on foot after a long and tiring cross-country train journey from Manchester. Despite his inauspicious arrival, His Royal Highness duly flipped the coin at the kick-off of the commemorative game – a repeat of the 1873 FA Cup quarter-final match against Oxford University – before the club sealed a 3-1 victory.

After the game the Prince stood up and announced he was hoping to secure a major sponsorship deal for the club. Instead of spontaneous applause, the Prince's announcement was greeted by embarrassed silence and the shuffling of chairs and napkins. Diplomatically, the club's chairman, Peter Griffin proffered a quiet word of thanks and farewell.

Club officials then investigated their royal patron, discovering a more down-to-earth truth: that His Highness was born Sid Halpern in Manchester. The prince was installed as the club's royal patron in 2008 in a move to match the Duke of Edinburgh's patronage of the club's rival, Windsor and Eton FC.

Steve Jinman, the club's director, said: "Our commercial manager found this guy called Frederick and he said he could do lots of good stuff for us and it didn't cost anything. But when we met him, everyone was a bit surprised because, for a royal, he, well, he seemed a bit more like the average guy in the street."

The Prince, 59, said that he inherited the title from his mother's family. "It was bought back from the Kaiser in the early 1900s. It is a purchased title, bought back after it was stolen in 1689. It's all on Wikipedia. I am remotely related to the Queen, yes. And all the sovereign houses of Europe, and the ones who are not reigning," he said.

Debrett's, the bible of royal and aristocratic lineages, was stumped by the Prince's claims. "The one reference to the duchy in the very early 18th century would suggest it is not a very significant one. The daughter of the Duke of Saxe-Lauenberg married into a collateral branch of the royal house of France. There's nothing after that other than a rather tenuous connection," a spokesman said.

Frederick – or Sid – lives in a Ruritanian idyll sometimes mistaken for a semi-detached house in Manchester's Withington area and is the patron of a number of charities.

He is also registered to a company called Children of the World 2000, a firm that has sparked a number of complaints over its charitable status. After the Charity Commission requested more information, an application for charitable status was withdrawn.

Mr Halpern remains adamant he has behaved impeccably, befitting his station as a royal. "It's not my title that defines me. It's what's inside – what your actions are. I have conducted myself above board and I have not crossed anybody at the ground. They were all delighted to see me and there is some hope to get the ground sponsored," he said.

"Under British law I'm officially not allowed to use my foreign royal title, but privately other royals know who you are. But on your passport it is Mr. It's like Princess Catherine of Yugoslavia."