Sir Ivor Roberts, the retiring ambassador to Italy, used his last official dispatch to accuse Labour of damaging British interests by ignoring expert advice.

The valedictory dispatch has become an institution over the centuries, giving a diplomat licence to speak his mind at the end of a career. But Roberts’s polemic, written this month, so angered the government that within hours Sir Peter Ricketts, the permanent under-secretary at the Foreign Office, withdrew the right of retiring ambassadors to pen a swansong.

Roberts, 60, now master of Trinity College, Oxford, wrote that foreign policy “could not be measured like hospital waiting lists”.

To illustrate his point, he writes scornfully of Stalin’s order to his foreign affairs commissar, Maxim Litvinov, to draw up a five-year plan for foreign policy in the early 1930s. Roberts said: “Diplomacy is about pushing rocks up hills and intercepting obstacles.”

Roberts also quoted a recent attack on Blair by Sir Rodric Braithwaite, former ambassador to Moscow and chairman of the Joint Intelligence Committee, in which he said he believed the prime minister and President Bush alone had “the key” to the problems of the Middle East.

Braithwaite also criticised the prime minister for reducing the Foreign Office to “a demoralised cipher”. He added: “He prefers to construct his ‘foreign policy’ out of self-righteous soundbites and expensive foreign travel.”

In his letter, Roberts painted a picture of a diplomatic service confused about its function and wasteful with taxpayers’ money. “If we spent more on conflict resolution, that is on classical diplomacy, we would spend less on reconstruction and peacekeeping,” he said, in a reference to Lebanon.

But he was also scathing about bureaucratic waste, claiming that the diplomatic service was “terrorised by management analysis forms”. He added: “I’ve been told that the Department for International Development [headed by Hilary Benn] has spent as much on management consultants as the Foreign Office has on its entire budget. We have overindulged in management consultancy.”

His criticism echoes a damning report, published in March by the cross-party foreign affairs select committee, which said the Foreign Office displayed a “woeful lack of professional skills”. The MPs also accused senior civil servants of trying to suppress criticism of the Foreign Office.

Roberts came to prominence when he was appointed charge d’affaires in Belgrade in 1994, rising to ambassador. He was accused of getting too cosy with Slobodan Milosevic, and too pro-Serb, charges which he vigorously denied.

During his tenure in Italy, Roberts caused uproar in 2004 when he accused President George W Bush of being the “best recruiting sergeant” for Al-Qaeda. His private comments, to a British-American think tank, were published in the Italian press, but dismissed by the Foreign Office.

Roberts’s message is part of a long tradition of frank valedictory dispatches by retiring ambassadors — most famously, that of Sir Nicholas Henderson, retiring ambassador in Paris,who in 1979 noted Britain’s decline to a second-tier power from the time he became a diplomat and Churchill and Attlee negotiated as equals with Stalin and Truman.

This weekend the Foreign Office confirmed that valedictory dispatches had been discontinued.

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Forces chief faces new battle - the economy
• Seven days that shook the world
• Icelanders wake up and smell ... the fish