The star of Inspector Morse spin-off Lewis has paid tribute to actor John Thaw, who made the Oxford-based detective series a worldwide hit.

Old School Ties, the first of three new two-hour long episodes starring Kevin Whately, starts on Sunday at 9pm and should attract millions of viewers.

Filming for the new episodes took place in Oxford last September after last year's pilot on ITV attracted 11.2 million viewers.

John Thaw died from cancer in February 2002. His screen alter ego died in the last Morse episode, The Remorseful Day, in November, 2000.

The series gave the dreaming spires of Oxford a high profile across the globe and has attracted thousands of tourists to the city.

Mr Whately said: "John carried the weight of Morse and drove it along, so Lewis has a very different dynamic and there's rather more responsibility on me. Morse was a fascinating character whereas Lewis was a sounding board, an Everyman, and initially I thought that it would be quite difficult to make a character like that interesting enough to carry primetime telly.

"In the end I was mostly persuaded by my wife, who said I'd have to drive it, and that it would be a different job to Morse - and that's what it feels like."

The Geordie actor, who also starred in Auf Wiedersehen, Pet, believes that John Thaw was "the best TV actor we've ever had". He added: "I'm not just doing myself down for the sake of it, but there was a quality that John Thaw had in his voice, an attack, which I've never got, so you just have to find a different way of driving it along.

"He just had this extra gear that was really impressive.

"Nobody ever mentions it because he was such a fine actor and the voice was all part of it, but it was really important for Morse - he could steam into somebody and reduce them to wreckage with one sentence."

The 56-year-old star said he and the production crew, many of whom used to work on Inspector Morse, often reminisced about the much-loved actor, who died of oesophagal cancer.

He added: "Memories flood back all the time - in one of the scenes this year we're in Exeter quad where Morse collapsed with his heart attack so you remember that, although I'm not aware of John peering over my shoulder."

Despite the fact that John Thaw's cerebral inspector was integral to the plot of the Lewis pilot and is alluded to in the three new episodes, Mr Whately is hoping the show will develop an identity of its own. Just like Morse, Lewis now has a sidekick of his own in the form of the fiercely intellectual James Hathaway, played by Laurence Fox.

In the first episode, it was revealed that Lewis is now living alone as a widower after his beloved wife was killed in a hit-and-run accident, and Mr Whately is adamant that his character won't have any love interests in the new episodes.

Eagle-eyed viewers will notice an anomaly with Lewis's force. Instead of Thames Valley he is now employed by the Oxfordshire Constabulary - which went out of existence 38 years ago.