Vince Cable has attacked the "ruthless" treatment of a group of British citizens forcibly removed from their homes to clear the way for a US military base.

The Lib Dem shadow chancellor waded into the long runnning row about the treatment of the inhabitants of the Chagos Archipelago in the Indian Ocean ahead of the first meeting of a new All Party Parliamentary Group (APPG).

"Let’s not forget that this is a long-standing injustice which involves a group of British citizens who were ruthlessly dispossessed of their homeland for reasons of military expediency," said Cable commenting on the fate of the 2000 islanders removed by the British authorities between 1968 and 1973 and dumped in Mauritius and the Seychelles.

"Many will say that it doesn't matter because the number of people affected is relatively small but I disagree. We are dealing with real people here. Worse, the whole thing has been enveloped in secrecy and denial by successive UK governments."

Cable says that he only became informed of the Chagos issue around a decade ago. And he reckons that until very recently "the level of awareness of Chagos among the vast majority of my fellow MPs was about zero".

The main reason, it seems, for most people’s ignorance is historical: the original deal struck in 1965 between the then Labour government led by Harold Wilson and the US authorities was done in secret by an exchange of notes without either British parliamentary knowledge or approval.

It hasn’t helped public awareness either that attempts over the last decade to rectify one of the most shameful episodes in recent British colonial history has been carried out almost exclusively through the UK courts despite the best efforts of a small number of MPs including Jeremy Corbyn and Tam Dalyell to raise it in the Commons.

But the launch of the APPG could change all this.

Chaired by Jeremy Corbyn it has an impressive list of 39 recruits so far - including Baroness Ludford, Lords Avebury and Steel and a number of senior MPs like Cable, John Bercow, Peter Bottomley, Kate Hoey, Austin Mitchell, and Andrew Tyrie (who has worked hard to find out the truth about the use of Diego Garcia, part of the British Indian Ocean Territory, for the purpose of extraordinary rendition by the US).

Significantly, it also includes three former Foreign Office ministers who had responsibility for Africa and the Indian Ocean – Tony Lloyd, Chris Mullin and Lord Luce.

The APPG is a firm and calculated response to Foreign Secretary David Miliband’s narrow victory in the House of Lords in October which ended the hopes - in the British courts, anyway - of the Chagos islanders returning to their homeland which lies 1200 miles north of Mauritius.

Lord Hoffman’s remark in his ruling - "the right of abode is a creature of the law. The law gives it and the law may take it away" – which backed the use of the royal prerogative (issued in 2004 while Jack Straw was in charge at the Foreign Office) in continuing the exile of the Chagos islanders has both raised awareness of their plight and caused significant unease at Westminister.

"A number of parliamentarians have pointed out that it depends what you mean by the law," explains the Chagos APPG coordinator David Snoxell, a former British High Commissioner to Mauritius. "Parliamentary law could not possibly have taken away the right of abode of the Chagos islanders. There would have been political uproar had the Foreign & Commonwealth Office tried to get "proper" legislation through Parliament."

As a career diplomat who knows something about the culture of government institutions Snoxell is keen to strike a co-operative note. "I am sure that the Group will want to work closely with the Foreign & Commonwealth Office in finding solutions to these issues," he says choosing his words carefully.

"It will also want to work with the Foreign Affairs Committee which concluded in its report, issued last year, that there was a strong moral case for the UK permitting and supporting a return to the British Indian Ocean Territory for the Chagossians," he adds.

The first substantive meeting of the APPG is scheduled to take place later this month and is expected to cover a variety of matters relevant to the Chagos islanders including environmental conservation, security, the future of the 1966 Anglo-American Agreement for the US military base on Diego Garcia - which comes up for renewal in 2016 - and British sovereignty of the Archipelago which is disputed by Mauritius.

Some commentators have suggested that the obvious injustice involved in the treatment of the Chagos islanders will soon find its way on to the radar of new US president, Barack Obama. Vince Cable thinks that this is unlikely, however. "It would certainly be nice if it did but let me just say that I would be pleasantly surprised if anything positive happened in the near future on that front," he says.

Nevertheless, Cable is keen to give some advice to David Miliband. "The Foreign Secretary should make himself aware of the history of this issue and see what can be done for the islanders even at this late stage. Injustices can very easily fester in overseas territories because it's been all too easy for Britain to shuffle off its responsibilities. The Chagos issue is an embarrassment that won't go away. It would be much better if the government decided to deal with it."

Dr Sean Carey is Research Fellow at CRONEM, Roehampton University