In an extraordinarily vitriolic tweet, Lord Alan Sugar — David Cameron’s recently appointed enterprise tsar — claimed it is “strange” that Gisela Stuart “a 1974 immigrant from Germany” was on the BBC debate’s Brexit panel “telling us British what we should do.”

Tonight’s BBC debate on the European referendum — focusing on immigration, the economy and Britain’s place in the world — was dominated by regurgitated talking points interspersed with sporadic moments of passion, often from the Leave supporters in Wembley Arena’s 6,000 strong audience.

Away from the main stage, however, reality television star and sometime entrepreneur Lord Sugar surprised many with a tweet targeted at one of the evening’s star performers.

‘Gschaider’ is the maiden name of leading Labour Brexiteer, Gisela Stuart — one of the Leave campaign’s strongest advocates. It is not a name she uses in her professional life, and Lord Sugar’s use of it betrays his frustration at prominent Brexiteers whose arguments he has previously labeled “ludicrous” and a “disaster” for the UK.  

The use of the Labour Member of Parliament’s German surname in a debate on the European Union (EU) has outraged figures on both sides of the argument.

Conservative Remain supporter, Sir Eric Pickles, defended Mrs. Stuart’s right to speak:

Conservative Brexiteer, Nadhim Zahawi MP, demanded an apology from Lord Sugar.

Another Twitter user even went so far as to accuse Lord Sugar of racism, a charge which he angrily denied.

Lord Sugar appeared to backtrack in later tweets, conceding that Mrs. Stuart is now British and claiming that he had been attempting to highlight the “irony” that an immigrant from Germany is “now telling us to control immigration from EU”.

LBC Radio presenter Iain Dale summed up the reaction of many to the original message, with an outraged tweet telling the peer he “should be ashamed of himself.”

Lord Sugar’s tweet and the reaction to it will cause embarrassment to his fellow Remain campaigners, not least to the Prime Minister for whom the recent appointment of the former Labour peer to his team was regarded as something of a coup.