Nanny's file marked 'top secret'

The nanny whose fast-tracked visa led to David Blunkett's downfall had her case given top-secret status, it is claimed tonight.

The Government faced fresh claims that there was a cover-up of the "nannygate" affair after a senior immigration source said the woman's case file was marked "restricted".

Leoncia Casalme, who was nanny for Mr Blunkett's ex-lover Kimberly Quinn, was granted leave to stay in Britain within record time after the Home Secretary's office got involved.

Files are normally marked "restricted" only if they have implications for national security and have been given special status at a senior level.

The Home Office refused to confirm or deny the claim, while the Tories today demanded a full explanation.

American-born Mrs Quinn's friends were, meanwhile, deserting her after revelations that she also had a relationship with Guardian journalist Simon Hoggart. They predicted she could be forced to leave London.

A senior source within the Immigration and Nationality Department (IND) revealed that the restricted classification was imposed on the nanny's file last year after Ms Casalme was given indefinite leave to remain in Britain.

It was found after the Home Office ordered a "paper trail" audit of all documents linked to her case. "I can't think of a Filipino nanny in the country who has this categorisation, other than this one," the source said. "It would suggest that somebody did not want her case to be widely known."

Shadow home secretary David Davis called on Sir Alan Budd's inquiry into the nannygate affair to check the fresh allegation. "It is extremely unusual that what would otherwise have been a minor case should receive the same sort of treatment as cases with national security interests," he said.

"Clearly these decisions would have had to have been made at a very senior level and reinforce our concern that a cover-up may have taken place as far back as 2003."

The Budd inquiry will reveal tomorrow that the Immigration and Nationality Directorate (IND) fast-tracked Ms Casalme's visa and that Mr Blunkett repeatedly made misleading statements about his involvement.

Mr Blunkett's office intervened in the application by faxing a letter to immigration chiefs. An emailed reply read: "No favours, but slightly quicker."

It emerged today that Paula Higson, the IND's deputy director general in Croydon, who is in charge of "managed migration", has been helping the Budd inquiry follow the "paper trail" of events.

She refused to comment about her role when asked by the Evening Standard about her role in the investigation.

In a little-noticed detail, Mr Blunkett admitted in a TV interview on the night he quit that the email came from "a deputy director general" at the IND.

It also became clear today that Home Office permanent secretary John Gieve could face the sack if the inquiry finds that he tried to stop a whistleblower.

Mr Gieve is alleged to have rowed with IND director general Bill Jeffrey over what exactly could be revealed to Sir Alan.

It was after this meeting that Mr Gieve told Sir Alan there was a paper trail which showed Mr Blunkett's private office had been involved, despite the former Home Secretary's denials.

Speaking at his Highbury home last night, Mr Gieve refused to comment saying: "I won't be making any statements."

The Budd report could also reveal lift the lid on why every Home Office officials went along with Mr Blunkett's claim that they couldn't remember a fax requesting fast-tracking or a "killer email" confirming the visa had been speeded up.

After senior immigration chiefs got involved, a female Higher Executive Officer helped process the nanny's claim in record time.

Mrs Quinn told Mr Blunkett she had been informed it could take a year to get the visa.