It has unearthed historical relics ranging from the remains of the first Spitfire to be shot down during the Battle of Britain to skeletons of Anglo-Saxon monks beneath Westminster Abbey, but after almost 20 years on air Tony Robinson's archaeology series, Time Team, is being buried by Channel 4.

Time Team has been one of the cornerstones of Channel 4's factual programming but it is being consigned to television history to make way for new shows.

Robinson, who played the luckless Baldrick in the hit BBC comedy Blackadder, said: "Not many performers are given the privilege of featuring in two iconic TV series – but I've been lucky.

"Time Team was not only high-quality public service television, it also attracted a large and passionate audience both in the UK and overseas. I'm proud to have been associated with it."

Time Team, which began in 1994, became a hit with viewers, with special editions such as The Big Dig in 2003 which dug up 1,000 sites around the UK live in a week. The show has been exported to more than 36 countries.

About four years ago, Time Team was attracting 2.5 million viewers, but recently appears to have lost its way.

A revamp designed to boost ratings was criticised by one of the show's regular experts, Mick Aston, who left, claiming it had been "dumbed down" and there was "a lot less archaeological content and a lot more pratting about".

The changes included hiring former model and Cambridge University archaeology postgraduate Mary-Ann Ochota. But she later left the show, saying the "series didn't work out quite how I wanted it to".

A special called Brunel's Last Launch, which aired last November, was watched by a smaller audience of 1.5 million.

Channel 4 said it wanted to focus on new and innovative history programming. "Channel 4 history is all about bringing the past to life in eye-opening, entertaining and innovative ways, from the best archaeological scoops, to big factual dramas," said Julia Harrington, the channels' commissioning editor for history.

New programmes include a documentary about the hunt for the remains of Richard III – called the King in the Carpark: Richard III – and a new series, the People of Stonehenge.

The final series of Time Team will air next year with a programme looking back at highlights from 250 episodes. There will then be four specials which will play into 2014.

Channel 4 head of factual Ralph Lee said: "I am incredibly proud that, as well as providing hundreds of hours of education and entertainment on Channel 4, Time Team has invested, over and above production costs, more than £4m in archaeology in Britain over the past 18 years."

Lee said Channel 4 was discussing "other ideas around archaeology" with Time Team's creator Tim Taylor.