Mark Leftly: He may be an octopus but the minister for everything has only got two hands

Westminster Outlook Michael Fallon is Westminster's – and the world's – first land-dwelling, four-limbed octopus, his tentacles wrapped around Whitehall, circular suckers incapable of being removed from powerful ministries of state.

However, David Cameron's most overworked minister doesn't lurk in the depths like his fellow cephalopods: this surgeon's son is forced to answer for his political actions in front of committees of MPs and lords far too often to spend even fleeting moments out of sight.

Rather, Mr Fallon's reach is extraordinary – not in the manner of a Lord Mandelson with his ethereal, mysterious "influence" – but physically. It seems that the former City stockbroking boss is almost everywhere in Parliament, virtually all of the time.

Now Mr Fallon has the opportunity to stretch those tentacles out of London as this month yet another full-time job, minister for Portsmouth, has been dumped on him. The 61-year-old has been charged by the Prime Minister with helping the city that is home to the wooden remains of the Mary Rose cope with BAE Systems' decision to close its historic shipyard there.

That's a third ministerial role to add to Mr Fallon's existing energy and business portfolios, which encompass – deep breath – building new nuclear power stations; privatising Royal Mail; promoting shale gas; sorting out the London 2012 Olympic "legacy" (as well as, presumably, working out just what that self-important yet vague word actually means); reviewing the Coal Authority; and dishing out North Sea oil exploration licences.

That's far from an exhaustive list of Mr Fallon's responsibilities, while he is also tipped as a future Tory party chairman. For good measure, he has, presumably, risked the wrath of the particularly vengeful god answered to by the Ukip councillor David "floods for gay marriage" Silvester, by arguing that the anti-EU party is still full of "fruitcakes".

No one doubts Mr Fallon's competence and intellect. Compare, for example, his performance against that of his boss at the business department, Vince Cable, during a November grilling over the privatisation of Royal Mail.

Mr Cable – features rapidly developing into William Gladstone's but without a trace of the Grand Old Man's exuberant verbosity – gave a masterclass in obfuscation as increasingly frustrated MPs sought an acknowledgement that the service had been sold off on the cheap at 330p a share. Mr Fallon, by contrast, gave the impression that he couldn't care less if the taxpayer had lost a couple of billion pounds because the shares had perhaps been underpriced when they debuted on the Stock Exchange. What mattered was to "protect the six-day-a-week service by ensuring there was a privatisation that meant there was a sustainable share price and the Government would not have to step in and provide any extra capital for this business".

While Mr Cable talked of judging the transaction in the "longer term", Mr Fallon took the criticism while rather artfully arguing that the price was never the point. Ensuring Royal Mail's commercial future and that the state would never again have to pour billions into guiding the service through any failures was far more important.

In boxing parlance, Mr Cable was a "runner", well out of range of his opponent but unwilling to engage and land any blows himself. Mr Fallon counterpunched, which, as any pugilist will tell you, is a far more effective tactic than throwing no leather at all. Long limbs and a good reach also help keep an opponent at bay, but Mr Fallon is, of course, only a figurative octopus.

He is, indeed, but one man and it's increasingly hard to believe that he can cope with all these jobs.

Towards the end of last year, and before he had responsibility for rescuing Portsmouth from what will inevitably be a leap in local unemployment, there was barely a day that went by when he wasn't up before a select committee, such as that inquiry into Royal Mail.

Which is why the Labour MP Alison Seabeck has just sent the Prime Minister a letter (rather cheekily addressed "Dear David") demanding to "know the range of responsibilities that Mr Fallon has been given for Portsmouth, beyond his duties specific to business and energy". There's little politicking here, as Ms Seabeck acknowledges Mr Fallon's skills even if she does not share his views.

And she is not alone in her opinion. The tasks of bridging our yawning energy gap, placing a mail service that has spent 500 years in the hands of the state into the private sector, and reviving a city that will lose one of its great sources of jobs should be divided among three people, not packaged up for one.

Some Conservatives have described Mr Fallon as being the PM's ghostbuster: "If there's something weird and it don't look good, who ya gonna call? Michael Fallon!" (readers under the age of 30 should probably type "Ray Parker, lyrics and Ghostbusters into Google).

However, Mr Cameron doesn't have to call Mr Fallon as he has more than 300 other MPs at his disposal, as well as 57 Liberal Democrats he could draw upon. And beyond that he could dip into the wealth of experience to be found among those not snoozing in the Lords.

Rather than an octopus or a ghostbuster, Mr Fallon could be described as the omnipresent polymath of Parliament.

That certainly sounds a touch grander than MP for Sevenoaks and Swanley – but that was, after all, the job he was elected to carry out.