Is Miranda Hart the new queen of TV?

The BBC's adaptation of Call The Midwife starts on 15 January. This 1950s drama about an order of nursing nuns is just the kind of thing for Sunday evening TV, combining a solid story with a touch of popular nostalgia.

However to some, the series' casting has offered up a bit of a surprise; comedy actress Miranda Hart is playing one of the midwives.

"Comedy will always be my first passion," Ms Hart recently told reporters, "but absolutely I think it will be amazing if I could have a career in which I could do both."

While it is unusual for a comedy actor take on a serious role, it is not without precedent. Over the years, we've seen some spectacular examples where such imaginative casting has paid dividends. Hugh Laurie in House, for instance, is probably the premier example.

Let's not forget Catherine Tate in Doctor Who (her success as Donna Noble is particularly laudable given how many sceptical Who fans she won over in the process).

Mind you, there are also those comedic casting experiments that have proven less successful. I for one was never convinced by Eddie Izzard's performance in US drama The Riches. Similarly, Mark Gatiss - a brilliant scriptwriter and comic actor - is just too hammy for my liking in his role as Mycroft in the otherwise exceptional Sherlock.

Miranda Hart for Doctor Who?

Yet while some might question whether Miranda really is the right choice for a serious bit of BBC telly, I think there is a bigger question which is being overlooked: why is Miranda Hart connected with pretty much any television series that's currently in production?

When Alesha Dixon announced her departure from Strictly Come Dancing, the press were quick to suggest Miranda was being lined up as a "left-field" replacement.

We were told the show's producers were looking for someone "really startling" to join Len Goodman, Craig Revel Horwood and Bruno Tonioli on the judging panel; apparently Miranda fit the bill.

Well, given she knows nothing about dancing, such an addition would indeed be "startling", although perhaps not for the reasons envisaged.

Happily, Miranda seems to have scotched that rumour. But, like a television hydra, chop down one rumour and another two will grow back in its place.

So next, we heard that Miranda was being lined up to appear alongside Amanda Holden on Britain's Got Talent; as ex-judge Michael McIntyre proved, a comedian on the Britain's Got Talent panel is no bad thing. However, ITV finally confirmed Alesha Dixon and David Walliams as the new faces. No Miranda.

If you believe the latest chatter, she's going to pop up in Doctor Who. Do we really want Miranda accompanying the Doctor on his travels once Amy and Rory depart (as they are scheduled to do over the course of the next series)?

And it's not just future telly projects. Over Christmas, Miranda turned up on such disparate shows as The BBC Sports Personality of the Year, The Big Fat Quiz of The Year, Michael McIntyre's Comedy Roadshow and Wild Weekend with Miranda (which saw her trek across the Alps with all-action man Bear Grylls).

Why is Miranda so hot at the moment? Her eponymously titled sitcom is an entertaining enough show, and the lady herself never comes across as anything less than likeable, but how has she come to dominate the schedules in this way?

Television is a strange beast and it is seldom possible to get to the bottom of exactly why certain talents suddenly become "hot" while others remain decidedly "not".

Take John Barrowman. Back in 2005, he was an accomplished song and dance man, but his television profile - beyond an aborted stint as a Saturday morning children's presenter - was pretty much non-existent.

It took just a single guest appearance in Doctor Who for the cheesy, but loveable, all-round entertainer to find himself in huge demand for pretty much any show going.

And to prove once and for all that the vagaries of TV are completely unfathomable, for a spell back in 1987, awful impressionist and old-school comedian Les Dennis could regularly be seen on BBC1 and ITV on a Saturday night - at the same time!

The ubiquitous Miranda Hart

In truth, I suspect certain celebs become hot property due to a media version of The Emperor's New Clothes. As soon as Miranda started to notch up the odd guest appearance, other programme makers probably began to wonder why she wasn't appearing on their show and took steps to remedy that situation.

Thus the cycle begins anew, with more TV bods spotting Miranda on more shows and so hiring her to appear on theirs.

This, of course, culminates with the inevitable point somewhere down the line, where those self-same programme makers decide en masse that Miranda's over-exposed and drop her like a hot potato.

This might not be good news for her, but it's great news for the phalanx of likeable enough comedy actors denied a spot on a panel show, or a cameo in a sitcom, because Miranda's already bagged it.

If you're convinced Miranda Hart's ubiquitousness is here to stay, seek out the opinion of poor old ex-flavour of the month Les Dennis and he will put you right - assuming you can track down exactly where he is, of course.

In the meantime, if you're a Miranda Hart fan - you've never had it so good. Let's see if she can successfully make the move into dramatic roles. And if she does, she will fully deserve her accolade as the queen of British TV.