A proposition of exquisite irony awaits Birmingham Conservatives, who have it within their grasp to take sole control of the city council – but only if they are prepared to sacrifice both their principles and their friends.

It is well known that Tory council leader Mike Whitby will become shadow mayor of Birmingham with all the powers of a mayor when the Localism Bill passes into law at the end of the year.

He will remain in that position until a mayoral election is held in May 2013, unless a referendum next year results in a majority of Birmingham voters saying they don’t want to be governed by a mayor, in which case Whitby can pack his bags and disappear.

What is perhaps not quite so well understood is that shadow mayor Whitby will have the power to select his own cabinet, which can have a minimum of two members plus himself, and that he can do this and almost anything else he pleases without gaining approval from city councillors.

In other words, in one glorious leap, the Conservative Party can wave goodbye to its Liberal Democrat coalition partners since 2004 and take sole control of Birmingham’s affairs at least until May 2013 – even if Labour gains a majority of council seats in the 2012 elections.

Will Whitby seize the moment? Will the man who campaigned against city mayors, as did most of his council colleagues, have the courage to grasp the levers of power and if he does will he adopt a slimline cabinet without Liberal Democrat membership?

Certainly, there is no reason why a Tory mayor should hand out cabinet posts to Liberal Democrats. Plenty of Conservative councillors would think it very odd if Whitby wanted to continue with the coalition arrangements when he really does not have to.

There is no reason why a city mayor should have a 10-person cabinet, since all of the power is channelled through the mayor. Two or a maximum three in the cabinet would seem to be appropriate, leaving Whitby with a major headache. Who to get rid of? Surely not Rudge, or Lines? Might be a case of bye-bye Les Lawrence and Randal Brew, however.

One is reminded of the quip delivered by grandee Tory Nigel Birch when Conservative prime minister Harold Macmillan sacked half his cabinet in an attempt to rejuvinate his failing government: “Greater love has no man than that he lay down his friends for his life.”

The dilemma facing Whitby can be seen from both a personal and party point of view.

On a personal level, becoming shadow mayor will give him an additional year in office that he never expected, given the likelihood of Labour gaining a majority of seats on the council in May 2012. It would also enable him to see through two projects that he regards as his prime achievements, construction of the new civic library in Centenary Square and the metro tram extension.