Tony Blair has completed his Cabinet reshuffle - sacking four ministers and appointing Jack Cunningham as 'Cabinet enforcer'.

A fly in the reshuffle ointment has emerged, however, with the resignation of Frank Field as junior Social Security Minister.

Those dismissed are:

• Harriet Harman (Social Security Secretary),
  
• Gavin Strang (Transport Minister),
  
• David Clark (Chancellor of the Duchy of Lancaster),
  
• Lord Richard (Leader of the House of Lords).

Coming into the Cabinet are:

• Peter Mandelson (Trade and Industry Secretary),
  
• Nick Brown (Agriculture Minister),
  
• Stephen Byers (Chief Secretary to the Treasury),
  
• Baroness Jay (Leader of the House of Lords and Minister for Women).

In addition, John Reid moves from junior Defence Minister to take over as Transport Minister. This post is no longer in the Cabinet, but Dr Reid will attend Cabinet meetings.

Peter Mandelson heads for a new job

Of the promotions, the one attracting most attention is that of Mr Mandelson.

Credited with being the brains behind Labour's election victory, he has more than his share of political opponents.

Chancellor Gordon Brown was reported to be opposed to Mr Mandelson having an economic department.

Mr Mandelson's new job is the first time he has had his own department to manage after spending a year as Minister without Portfolio in charge of the Millennium Dome.

He has instigated one change already - deciding not to be known like his immediate predecessors as President of the Board of Trade, a title he described as "pompous".

New 'Cabinet enforcer'

Things are looking up for Jack Cunningham

The reshuffle is centred around the appointment of Dr Cunningham as a Cabinet 'policy enforcer' with a wide-ranging brief.

This will include co-ordinating government policy as well as presenting it to the public.

Mr Cunningham is a veteran who served in the last Labour government in 1979 and has recently been dealing with the BSE problem as agriculture minister.

Shifting sideways

As well as sackings and promotions, there have been a number of sideways moves within the Cabinet.

Margaret Beckett moves from Trade and Industry to become Leader of the Commons. She will also support Dr Cunningham in presenting government policy.

The current Commons leader, Ann Taylor, will be made Chief Whip, which now becomes a Cabinet position.

Alistair Darling, formerly number two at the Treasury, gets his own department at Social Security.

Shock for Harman

Harriet Harman: Victim of Blair's axe

The biggest surprise among the sackings is that of Ms Harman.

She was believed more likely to have been moved to a less high-profile job after a difficult year, but not dropped from the Cabinet completely.

Ms Harman has also lost her secondary role as Minister for Women, which goes to Baroness Jay, the new Leader of the Lords.

The release of Mr Clark and Mr Strang had been strongly rumoured for some time.

Field prompts greater changes

On his way out: Frank Field

The resignation of Frank Field will force the prime minister into making more changes than he planned.

It is believed that Mr Field wanted to be promoted to the number one job in his department but was not offered it or a suitable alternative.

Mr Field, who was in charge of changing the benefits system, said as he left Downing Street:

"Welfare reform is a central subject for this government. I believe I can support the prime minister more effectively from the back benches to achieve that objective rather than any of the positions discussed for me."

Tony Blair is now turning his attention to the junior ministers, but the changes will not be announced until Tuesday.