13 November 2012 Last updated at 09:03 ET

Ed Richards is new favourite for next BBC director general

Ed Richards was appointed chief executive of Ofcom in October 2006

Ofcom boss Ed Richards has emerged as the bookmakers' new favourite to become the BBC's next permanent director general, with the BBC Trust known to be considering external candidates.

Richards, 45, was linked to the job prior to the appointment of George Entwistle, whose resignation after eight weeks led to the appointment of Tim Davie as acting DG.

Richards was a senior advisor to former Prime Minister Tony Blair - his other previous jobs include controller of corporate strategy at the BBC.

As chief executive of media regulator Ofcom he has overseen the regulation of the TV and radio sectors, fixed-line telecoms, mobiles and postal services.

In 2009 The Guardian described Richards as "one of the key architects of Britain's media landscape in the digital era".

Yet others have been less complimentary. In 2003, former director general Greg Dyke famously referred to him as a "jumped-up Millbank oik" at a Royal Television Society conference.

Davie, the director of BBC Audio and Music, is second favourite to land the position according to bookmakers Ladbrokes and Paddy Power.

Both name Caroline Thomson, the BBC's former chief operating officer, as their third favourite to become the corporation's next leader.

Thomson, who was on the final shortlist earlier this year, left the BBC after her job disappeared in a corporate restructure in September.

Analysis Torin Douglas Media correspondent

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Because the BBC Trust wants to see a complete overhaul of the BBC structure and management, Lord Patten is thought to favour an outsider. That makes sense - but there are problems with appointing someone from outside the corporation.

They may want to be paid more than is politically acceptable, given the fuss over George Entwistle's £450,000 salary and pay-off.

It may take longer for an outsider to take up the post, if they are in a significant job already.

The level of public scrutiny is higher than most other jobs, as Mr Entwistle found out in his 54 days in the post.

And, unless they've worked at the BBC before, it is likely to take them a long time to find their way around its labyrinthine corporate structure.

It is often forgotten that Greg Dyke, the last outsider to be appointed, joined the BBC five months before he took over - as director general designate - so he could learn the ropes.

All that points to an outsider who has worked at the BBC before.

Candidates could include Ed Richards, the chief executive of Ofcom, who was a candidate last time and a former controller of strategy at the BBC; Tony Hall (Lord Hall of Birkenhead), chief executive of the Royal Opera House and a former director of BBC News; and Sophie Turner-Laing, managing director for entertainment and news at BSkyB, who was once acting director of television at the BBC.

Then there is Caroline Thomson. Formerly chief operating officer at the BBC, she was on the final shortlist this year only to see her job disappear when George Entwistle restructured the corporation in September.

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As she left the organisation she praised the BBC for its "wonderful" programmes, her "brilliant" colleagues and the organisation's "real sense of public purpose".

Other internal candidates who are believed to be in contention include Danny Cohen, the head of BBC One and a former controller of BBC Three.

Yet because Lord Patten, head of the BBC Trust, is thought to favour an outsider, a range of new possibilities has come into view.

According to the Times, one name being "talked up" is Tony Hall, chief executive of the Royal Opera House and the BBC's former director of news.

Other ex-staffers whose names have been mentioned include ITV's director of television Peter Fincham and Channel 4's chief creative officer Jay Hunt, both of whom are former BBC One controllers.

Michael Jackson, a former chief executive of Channel 4 and one of the few to serve as controller of both BBC One and BBC Two, is another potential candidate.

So is Mark Scott, managing director of the Australian Broadcasting Corporation, and Dawn Airey, the former chief executive of Channel 5.

Lord Patten has said a new director general will be appointed within the next few weeks.

One individual who seems to have ruled himself out of the running is David Dimbleby, host of BBC One's Question Time.

The veteran broadcaster told the Daily Mail he was too old to be offered the position, despite there being no age limit attached to the post.