Who Do You Think You Are? (BBC1, 9pm)

I HAVE only too painful memories involving the fact that Martin Shaw doesn’t want to discuss anything to do with the ITV series which made his name, The Professionals. Having read that Shaw, who has moved on to more serious dramas like Judge John Deed and North-East-made Inspector George Gently, no longer wanted to discuss his perm-topped action man days alongside Lewis Collins, I was once delighted to see that Shaw mentioned The Professionals in publicity for a series being launched in London.

Having found my way through a maze of corridors to be first at the launch, I discovered Shaw in a distinctly non-Professionals mood and opting for a bit of a silent sulk. Into that rather frosty atmosphere walked a gaggle of other entertainment reporters. The first, from The Daily Telegraph, assailed the great men with a question about The Professionals. Thankfully, Shaw caved in at that point, started talking and stopped giving the impression of someone about to heave my fragile frame over the nearby balcony.

Shaw was born in Birmingham in 1945, and made his debut in an amateur production alongside his parents at the age of three. In the 1960s and 1970s he appeared in Look Back in Anger and Saturday, Sunday, Morning and regards his role as Stanley Kowalski in a 1974 production of A Streetcar Named Desire as a turning point in his career. Regular returns to the stage saw Shaw appearing in Twelve Angry Men in the West End last year.

For the fascinating series about ancestry, he's keen to find out more about his paternal grandfather Edwin, who enlisted in the Royal Marines at the age of 18.

"My grandfather Edwin is a bit of a mystery because he was kind of persona non grata, nobody talked about him very much," says Shaw. "There was always a kind of painful silence and a painful information blackout about Edwin. It was as though this huge tragedy went into my father's family – I think my dad said that Edwin left them for another woman.

"I've only got one picture of Edwin, he was referred to as Ted, if he was referred to at all, which wasn't very much. My dad said when I asked him about this picture that Edwin was 17 when this was taken. It's a military uniform and we had no idea what the uniform was until my brother very cleverly zoomed in on the cap badge and he determined that it was the Royal Marines - so we are almost sure that Edwin was in the Marines, but that's it, the rest of it is a complete blank."

Britain's Craziest Commutes (Channel 5, 8pm)

AMONG the long-distance travellers are a single mum, who has a daily trip from the Isle of Wight to London - and it takes her three hours, each way. An islander from Scotland commutes 300 miles using three different forms of transport to get to his office in Glasgow, a man journeys from the South of France to Bristol, spending £600 a week. Cameras also follow one London commuter whose 11-mile drive can take him up to two-and-a-half hours, while a man from Derbyshire cycles 28 miles to and from work each day.

Scotland Decides (BBC1, 10.35pm)

IT’S been one of the most talk-about political topics for the last year or so, but today marks Scotland’s decision on necoming an independent country. Huw Edwards presents live coverage from Glasgow, as the votes are counted. BBC Political Editor Nick Robinson and Scotland 2014's Sarah Smith will be on hand to present the commentary, and Jeremy Vine's Virtual Reality graphics will help us see how the vote is building up throughout the night. Elsewhere, Andrew Neil is in Westminster, and there are teams in Wales and Northern Ireland as well to bring all the latest reaction.