Labour MP Jack Dromey accused of racism after calling Royal Mail worker 'the Pikey' on Twitter Shadow police minister lands himself in hot water after latest web gaffe Married to staunch PC campaigner Labour deputy leader Harriet Harman Posted photo of Royal Mail worker after touring Edmonton sorting office He wrote that he was with 'Gareth Martin, the Pikey' above a picture Twitter users accused him of racism and warned he might have broken law Inists it is a Dad's Army-inspired nickname but Labour says it was 'stupid' The police have been urged to investigate gaffe-prone Labour MP Jack Dromey after branding a postman "pikey." Labour insiders were furious when the shadow police minister, who is married to deputy leader Harriet Harman, posted the controversial caption with a photo of himself with Royal Mail staff on Twitter. Tory MP David Morris tonight wrote to Metropolitan Police Commissioner Bernard Hogan-Howe claiming it was an 'incident that may constitute incitement to racial hatred' and asking him to launch an inquiry. Offensive: Labour MP Jack Dromey faced criticism after referring to Royal Mail employee Gareth Martin as 'the Pikey' in a tweet Mr Dromey has fallen foul of social media before and just last month he was left red-faced after it emerged he added a Twitter link to a gay porn website to his list of "favourites." In the latest web blunder he attracted criticism online after writing: "With Gareth Martin, the Pikey from the Erdington Royal Mail Sorting Office. A great guy! Since 2007 it has been possible to be arrested for a racially aggravated offence for using the word "pikey," which is an offensive word used to refer to Irish travellers. After facing a storm of criticism online, Mr Dromey moved to insist that it was a nickname used by Mr Martin's colleagues who had named him after a Dad's Army character. But Labour party insiders condemned a "stupid choice of words." It is especially embarrassing because Ms Harman is a long-standing campaigner on equality and political-correctness. Tense: Mr Dromey is married to deputy Labour party Leader Harriet Harman After posting the controversial message, Mr Dromey was bombarded with criticism from other Twitter users. HammyWheel wrote: "Disgraceful incitement to racial hatred there? "Pikey" is a horrid thing to call anyone. Expect a knock on your door from Plod. Guy Birchall added: "Worse than calling a policeman a pleb. Disgustingly insulting behaviour! Melindi Scott simply added: "Raaaaaaaaaaaacist" After the backlash, Mr Dromey insisted he had used the racially-loaded word because it was used by Royal Mail staff. In a later tweet he wrote: "Don't panic, Mr Mainwaring. This morning's meeting was with Gareth, a Postie nicknamed after Corporal Pike from Dad's Army. Nickname: Mr Dromey insisted that Royal Mail staff used the name 'Pikey' in reference to Private Pike (right) who featured in 1970s sitcom Dad's Army alongside Captain Mainwaring Iin his letter to the head of the Met, Mr Morris claimed he had received a number of complaints about the tweet from members of the traveller community in his Morecambe and Lunesdale seat. Mr Morris wrote: 'As I am sure that you are aware, the word "pikey" is a deeply offensive word, and is a racially charged term due to its association with Irish travellers and Roma gypsies. I have received a number of complaints from members of the travelling community in my constituency, and am writing on their behalf. Crown Prosecution Service guidance as you know states that an "offence is committed when the accused person says or does something which is threatening, abusive or insulting and, by doing so, either intends to stir up racial hatred, or makes it likely that racial hatred will be stirred up." Mr Dromey is not only a high profile politician, but is also Shadow Minister for Policing. His tweets reach a wide audience, and he is in a position of some authority. I would be very grateful if you could investigate this incident as a matter of urgency. Letter: Tory MP David Morris, who has asked the police to investigate the tweet, spent the day with Prime Minister David Cameron A Royal Mail spokesperson said the term "Pikey" was not commonly used in its sorting offices. She said: "I can confirm there is no such slang term for a role within Royal Mail delivery offices." A Labour party source said: "This is his nickname. It was a stupid choice of words. He should have realised that it could be open to misinterpretation and when he did, he clarified it. He made a silly mistake but he referred to Pikey as that is the man's nickname after the well-known character in Dad's Army. It is not meant to refer to him being a gipsy. In November Mr Harman linked to a tweet about well-endowed black men. The link showed a picture of two men engaged in a sex act. Back in September, he also favourited a link to a Tweet on a similar theme. Mr Dromey said he had accidentally stumbled on the gay porn website - which featured a character called "Paris."