OUR man in Havana and the staff in other embassies worldwide are supposed to be the frontline ambassadors putting the best shine on Britain’s image abroad.

Back home it is a different story. A damning report has painted a picture of the Foreign and Commonwealth Office (FCO) as full of incompetents, “cowards” and “clones”.

Films like Carlton-Browne of the FO, starring Terry-Thomas, used to portray the pin-striped failures of British diplomacy. The upper-class twits may have been replaced by a new generation of bright young ethnically diverse civil servants, but they are being ruined by inertia and ineffective leadership, according to the study.

In the report, which the FCO has suppressed, management consultants mourn the “tragic” descent into mediocrity of a once fine institution, expressing disbelief at the culture that operates in the offices behind closed doors at its imposing Whitehall headquarters.

“From the minute one walks into [the] buildings, the office feels second-rate. That the professionalism and spirit of the vast majority of officers shines through this is a cause for celebration, amazement even,” it says.

The FCO commissioned the “cultural audit” by Couraud, the human resources consultancy, last year as part of an effort to improve performance. The mortifying results only came to light when a copy of the report, submitted last August to David Miliband, the foreign secretary, was slipped into the House of Commons library last week.

It makes excruciating reading for ministers, saying the once well oiled diplomatic machine is in danger of descending into “stagnation and decay” as it is throttled by “uncertainty, political jockeying and vacillation”.

Every section of the 42-page report, which covers leadership, decision making, communication and the working environment, is critical.

The consultants carried out in-depth interviews with about 50 FCO staff at varying levels of seniority. Their report describes how even the brightest and best are reduced to automatons “submitting wholesale to the culture of committees, sub-committees, working groups and steering groups”.

It says: “It recruits bright people brimming with independent thought, but then proceeds both intentionally and unintentionally to apparently ‘clone’ them.”

An embarrassing chapter paints a picture of hapless diplomats returning from overseas postings and being forced to “beg, borrow or steal passes to enter buildings” because nobody has prepared for their return.

Admonishing those at the top, it says witheringly: “From what participants told us, effective leadership would go a long way towards curing some of the issues and problems [we] set out.”

Miliband is not named in the report but will shoulder some of the blame. The foreign secretary, fresh from embarrassing photographs of him gurning with a banana at last year’s Labour conference, scored a diplomatic own-goal on a visit to India in January when he upset one of Britain’s last allies.

He insisted that the Indian government should sort out the problem of Kashmir, the failure to do so being a direct cause of the terrorist attacks in Mumbai which left almost 200 dead. India begged to differ, just as it had when the late Robin Cook made a similar gaffe in 1997.

The consultants say they were particularly struck by the “fear of failure” pervading the FCO: “Participants told us too many unhappy stories of obviously moribund projects not being scrapped because no one who could or should have admitted failure was prepared to do so. Quite simply, there is no excuse.”

It adds: “Perhaps most depressingly of all . . . officials are reaching the very top . . . by never making any mistakes.”

The report praises the organisation for embracing 21st-century management ideals such as meritocracy and the promotion of gender and race equality. But it claims the pendulum has “swung too far the other way” with “consensus building at almost any cost”.

It accuses staff of indulging in endless debate even after decisions have been taken, adding: “Dissent after the event is inexcusable and speaks of the worst excesses of one of the darker sides of the office’s culture , the cult of the cowardly ego.”

More seriously, it suggests that diplomats abroad are being gradually “disposessed” as decisions are increasingly taken in Whitehall.

In a counsel of despair, the report concludes: “We have never come across an organisation so stuffed full of talent. How can it continue to get so many obvious ‘common sense’ issues wrong?”

Yesterday the Foreign Office put a brave face on it. A spokeswoman said: “It has stimulated a lot of good debate in the FCO. The report was based on replies from a relatively small number of staff.”

What a carry-on

Some of Britain’s diplomats have earned a reputation for weakness or bungling.

- Officials blundered in their response to the 2004 Boxing Day tsunami. The main Foreign Office emergency response team was sent to Sri Lanka rather than Thailand, the country with the largest number of British victims. The ambassador to Bangkok, David Fall, was criticised for dithering and incompetence.

The defence attaché, Peter Roberts, was later said to be suffering from “tsunami-related post-traumatic stress” after an incident on a homeward-bound plane.

- The FCO’s greatest embarrassment of recent years was Craig Murray, the ambassador to Uzbekistan, sacked in 2004. He claimed he was removed for exposing human rights abuses by the regime and boasted in a book of drinking exploits in Tashkent and his romance with a nubile 22-year-old, 20 years his junior, which ended his marriage.

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