David Cameron's policy chief has been forced to "unreservedly apologise" after accusing Britain's black communities of having a "bad moral ­attitude" in the wake of a 1985 riot in north London. Oliver Letwin, a former adviser to the Margaret Thatcher and now minister in the current Conservative government, issued the statement after the publication of government papers dating back 30 years.

The release of the private memo revealed that Letwin had blamed the unrest on "bad moral attitudes" and the Old Etonian had advised against helping young, black entrepreneurs because they would spend the government funding on discos and the drug trade. The comments were condemned by Labour, and Streatham MP Chuka Umunna blasted the document as "disgusting and appalling".

"The authors of this paper illustrate a complete ignorance of what was going on in our community at that time, as evidenced by their total and utter disregard of the rampant racism in the Met Police which caused the community to boil over – there is no mention of that racism in their paper," the former shadow business secretary added.

"The attitudes towards the black community exhibited in the paper are disgusting and appalling. The tone of it in places is positively Victorian. People will draw their own conclusions but I hope the authors will feel thoroughly embarrassed and ashamed at what they wrote back then. At the very least they should apologise."

But the scandal is not the first high profile controversy Letwin has been embroiled in. The 59-year-old has come under fire for dumping government documents in public bins and for urging Thatcher to use Scotland as a testing ground for her controversial Poll Tax, otherwise known as the Community Charge.

Trail-blaze Poll Tax in Scotland

"If you are not willing to move to a pure residence charge in England and Wales immediately, you should not introduce a mixture of taxes, but should rather use the Scots as a trail-blazer for the real thing," Letwin wrote, according to memo released by the National Archives.

The documents also showed that some Tory ministers were opposed to the levy and former chancellor Nigel Lawson even blasted the proposal as "completely unworkable and politically catastrophic". But Thatcher pressed ahead and rolled out the flat-rate tax in Scotland in 1989, and in England and Wales in 1990.

The move would prove fatal for Britain's first female prime minister as public opinion swung against Thatcher and triggered a coup against her within the Conservative parliamentary party, led by Michael Heseltine.

Beg for school fees

Letwin made an embarrassing apology in 2003 for apparently saying he would rather beg for private school fees than send his children to a state school in Kennington.

"I regret that a particular school was identified by the London press," he told Sky News. "I have written to apologise to them because I would not want to cause any offence I did think it caused them."

Letwin was serving as the shadow home secretary at the time and later that month Iain Duncan Smith quit as Tory leader after he failed to win a vote of confidence from Conservative MPs.

Park life

London's St James's Park was the scene of another of Letwin's gaffes in 2011. The then Coalition Government cabinet minister was caught by The Daily Mirror dumping more than 100 parliamentary papers in a public bin in the park. Letwin stressed that the documents were not classified and apologised to his West Dorset constituents.

"I was walking around dictating responses and simply wanted to make sure the pieces of paper were not weighing me down. I have to apologise to constituents who have written to me because, on reflection, I shouldn't have disposed of them in that way," he told the BBC.