He has two hearts, travels in space and time in a blue box, and has defeated a myriad of evil aliens - but more importantly has been part of my life since the mid 1970s.

My formative years were spent watching Tom Baker battling all manner of sinister menaces such as Davros the creator of the Daleks, a decaying Master, a shape shifting Rutan, giant rats and Sontarans.

•'I have Doctor Who to thank for what I do now'

And as I watched the scarf wearing Doctor and his faithful companions, such as Sarah Jame Smith, Leela and K9, use their wits to send aliens to their doom, the programme soon became my favourite and still is today.

A large part of the show's success is the eccentric and mysterious character of The Doctor, who relies on his Time Lord brain to defeat his foes by the end of every adventure - instead of just picking up a ray gun or laser.

As each adventure ended on the television in my boyhood living room there was a sense of strong anticipation as to where The Doctor's next journey in the Tardis would lead him to, from a far distant planet to the sewers of Victorian London.

And it seems that today's youngsters are just enthralled by the same factors as I was as every week they tune in to watch the current Doctor Matt Smith outwit his foes while espousing the virtues of bow ties at the same time.

As the 11th Doctor prepares for his greatest adventure tonight it is a tribute to one of the most innovative and surprising character changes to ever take place in television history - regeneration.

I will never know what it felt like as a Doctor Who fan in 1966 when they saw their hero William Hartnell regenerate into Patrick Troughton after battling the Cybermen in The Tenth Planet.

But I still remember the shock in 1981 when Tom Baker seemed to fall to his death in the story Logopolis and then changed into a youthful Peter Davison.

However thanks to the central tenets of the programme, that anywhere in time and space was a possible destination and there were a horde of threatening alien villains out there, I soon settled down and enjoyed my new Doctor.

Talk of villains and aliens of course leads to the another factor in Doctor Who's popularity and which helped propel it into the nation's conscious - the Daleks.

The pepperpot mutants inspired whole generations children to shout out 'Exterminate' and they are firmly the most recognisable aliens in British culture.

And it must be said there is another reason why Doctor is fondly thought of and gently ridiculed- its wobbly sets, over acting and men in rubber suits, such as the marsh men of Alzaruis.

However I can put those flaws to one side as the character of The Doctor, the power of imagination and a fear of the unknown continue to keep my flame alight for the programme.

And I hope I can have another 50 years of settling down in front of the television to watch a science fiction legend take on a set of new foes, with hopefully some old ones thrown in as well for nostalgia's sake, such as Ice Warriors and Yeti.

So happy birthday Doctor Who and thank you so far for saving the earth and Universe!