By Keily Oakes
BBC News Online entertainment staff
The Likely Lads led the comedy field on BBC Two
BBC Two, which has turned 40, hit the airwaves in 1964 armed with a remit to broadcast a more experimental style of TV than its sister channel BBC One.
As well as providing viewers with images in colour, it also gave them the luxury of a third channel, having had BBC One since 1936 and ITV since 1955.
But BBC Two was launched less in a blaze of glory than a dark disaster - a power cut wiped power from Television Centre, forcing the opening night schedule to be aborted.
And because the new channel was broadcast using the latest technology it was available only to viewers who purchased a new television set able to receive it.
This led to accusations it was a channel for the well-off because lower classes could not afford to buy another TV.
BBC Two took time to find its feet - and viewers - with schedules overhauled regularly to try and find a winning formula.
Part of its evolution included revolutionary colour broadcasts, beginning with Wimbledon coverage in 1967, although they were not available everyone.
It beat BBC One and ITV to broadcasting in colour by two years.
The channel also had a very famous face as its controller between 1965 and 1968 - Sir David Attenborough.
It was during his era that seminal programmes such as Man Alive premiered, but probably the biggest TV event screened during this period was mini-series The Forstyte Saga, which became one of the first-must see costumes dramas.
It went on to win a Bafta and an Emmy for actress Susan Hampshire.
Hampshire told BBC News Online: "I was very lucky to have such a wonderful part in a series that was not only popular but that has been recognised as extremely good television."
BBC Two has also gained a reputation for creating ground-breaking comedies from the satirical Not the Nine O'Clock News in the 1970s, to the Young Ones in the 1980s.
It also saw the debut of The Goodies in a late night slot.
Goodie Tim Brooke-Taylor told BBC News Online: "We had a very good relationship with all the BBC Two controllers. They knew we were slightly left of centre and that was what BBC Two was all about. They took a chance on us.
"BBC Two allowed us time which meant we could take risks, develop them and run with it."
But Brooke-Taylor acknowledged one of the best decisions made was to move The Goodies to an earlier slot on BBC One, although he was against it at the time.
Golden Globe-winning comedy The Office started life on BBC Two, carving out a dedicated audience.
Despite resistance from creator Ricky Gervais, who called BBC Two the "spiritual home" of The Office, the show was moved to BBC One for its Bafta-winning final episodes last Christmas.
BBC Two's evolution is continuing with the expansion of the digital market.
The launch of channels including BBC Three and Four means it is now sharing the limelight as a testing ground for new shows.
Bafta-winning cult comedy Little Britain, created by Matt Lucas and David Walliams, started life on BBC Three.
Word of mouth praise, and cult status saw the show's digital audience rise prompting the entire series to get a run on BBC Two.
BBC Four has also arguably taken some of the limelight because its remit was to show high-brow cultural TV, something BBC Two had been traditionally seen to encompass.
John Hurt criticised spending on dramas
Actor John Hurt vented his wrath on the subject following the filming of drama the Alan Clark Diaries, which was produced for BBC Four.
He hit out at tight budgets and said the drama was one that would have traditionally been shown on Two, but had been sidelined to Four.
"What did BBC Two first do? Didn't it provide us with something a little bit more interesting than we thought we were ready for? Isn't that what it was there for?" said Hurt.
However broadcaster Lowri Turner, who worked on Would Like to Meet and Looking Good, praised progress made by the channel.
"BBC Two, first under Mark Thompson and then Jane Root, became very brave in its commissions," she told BBC News Online.
"Years ago it was a dusty old channel doing things like foreign war documentaries and I never watched it.
"Then they suddenly realised it could be popular and do lifestyle shows in a way that was different from those on BBC One or ITV."
BBC Two is still considered highly in the competitive world of TV, winning terrestrial channel of the year at the Edinburgh Television Festival in 2003.
But the channel faces further challenges as it enters it 41st year.
One change will be the loss of The Simpsons, which will soon move to Channel 4, a show which appealed to the younger demographic.
And with the imminent departure of controller Jane Root the future of BBC Two is uncertain - whoever takes over will surely want to put their own stamp on the 40-year-old channel.
Happy Birthday BBC Two is being screened on the channel on Tuesday evening at 2000 BST, featuring people who have worked both behind and in front of its cameras over the years.