TEEN drama Skins returned to E4 this week. But for the second time followers would be hard pushed to recognise any of the regular characters. Once again there’s been a clearout of the cast.

New term at college means a new bunch of hormonal students with satchels full of angst and teen problems. Rather than prolong their education and end up with 30-something actors playing students, the series swaps old for new. It was a bold move but worked the first time for Skins, so series five starts all over again... again.

The comings and goings of characters isn’t unusual in soaps or series like Doctor Who, which has body swaps written into the Time Lord rules. But deliberately switching actors is more unusual in drama when it’s not necessary because viewers feel more comfortable with what they know and love.

Some series even manage to carry on without the leading actor. Long-running detective series Taggart is the prime example of a show that’s still going strong despite the fact that the title character is nowhere to be seen. The Glasgwegian cop first appeared, played by Mark McManus, in 1983. When he died in 1994, the producers decided to carry on without him, but retain the name in the title.

The BBC sci-fi series Blake’s 7 carried on for several series after Roj Blake disappeared into outer space at the end of the second series because actor Gareth Thomas wanted to move on.

The smoothly villainous Avon (played by Paul Darrow) took command of the renegade band of resistance fighters, although Blake did pop back for the final episode.

Robin Hood has appeared in many incarnations on screens big and small. But the Eighties series featured two different actors as the man with the longbow and arrows. When Michael Praed opted to leave Robin Of Sherwood for glossy US soap Dynasty, he had a change of character – and turned into Jason Connery. Lovers of useless facts noted that his father Sean Connery played the older Robin Hood in the movie Robin And Marian.

Audiences stayed mainly faithful when Praed left, but The X-Files without David Duchovny’s FBI agent Fox Mulder was unthinkable for fans. The last two seasons, featuring a new agent played by Robert Patrick, passed by without anyone paying much attention – although Duchovny did reprise the role for a second X-Files movie.

Cold Feet struggled on when Fay Ripley left after the fourth series, until the makers called it a day after another cast member, Helen Baxendale, got itchy feet. The series ended with the death of her character, Rachel. In the US, hit comedy Friends managed to retain its six stars for a nine recordbreaking seasons, something that may have been linked to the huge pay cheques they all received to stay loyal to the show.

Successful British series make a habit of changing faces, usually prompted by stars gaining fame and wanting to move on to something bigger or better.

Peak Practice started out with Amanda Burton and Kevin Whately. When they left, different doctors moved in. Burton moved on to success as forensic pathologist in Silent Witness. Again, when she left others were brought in to replace her and the tenth series is currently running on BBC1. She’s currently moved to school series Waterloo Road.

Heartbeat regularly swapped young police constables to patrol the Yorkshire countryside beat after original star Nick Berry left. The uniform was the same and so were the plots, but the face under the police helmet was different.

Where The Heart Is debuted with Sarah Lancashire and Pam Ferris as its stars. After their departure, a variety of familiar faces were recruited to keep the Heart beating, including Denise Van Outen and Lesley Dunlop.

Last Of The Summer Wine found a seemingly endless supply of veteran actors to make up the trio of old codgers at the heart of this gentle Yorkshireset comedy series.

Martin Clunes and Neil Morrissey are widely remembered as the stars of BBC comedy hit Men Behaving Badly. Not so many recall that the series started out on ITV with Harry Enfield partnering Martin Clunes.

The new Skins cast have a lot of growing up to do in a short time – their young TV lives will be cut short after just a couple of years and they’ll be looking for work. Just like real students, you might say.