During the early years of colour television in the UK, videotape recording remained very expensive and videotapes were thus often reused or junked at a later date (either accidentally or deliberately for a variety of reasons). As a result there aren't all that many colour videotape recordings surviving from before the mid seventies.
Recordings of television programmes during the early years of colour were sometimes made by pointing a film camera at a studio monitor, but for reasons of cost and expediency the film used was black and white. Some of these film recordings became the only surviving copies in existence when original videotapes were later reused .
It is somewhat ironic that many surviving programmes from this early period, including landmark drama productions such as Nigel Kneale's The Year of the Sex Olympics, only exist nowadays in monochrome as opposed to the sometimes garish new colour that a few lucky viewers experienced when these shows were first transmitted.
Most of these black and white 'telerecordings' as they are known, contain a potentially useful secret. Much of the information relating to which colours make up the image is concealed in the monochrome picture in the form of a barely visible pattern of dots.
If a computer program could somehow analyse this pattern and extract the hidden information that may be contained in each frame of film, it could be possible to restore the missing colour to the image.
This idea was suggested a few years ago but until very recently it remained just an unproven theory with various highly complex technical problems to be resolved. Fortunately this didn't deter a small group of talented and experienced individuals from pooling their expertise to see if such a colour recovery process was feasible.
In recent weeks some significant progress has been made by this group and although there are still some remaining technical issues, the development of a colour recovery system has now reached the stage where the technique has produced some extremely encouraging results, as can be seen below.
The colour restoration process is obviously affected by glitches in the stock but for many good quality film recordings it seems that the ability to restore the lost colour from them has not only been successfully proven but is on the verge of becoming practicable; other restoration techniques could also be used to improve the final result.
It's ironic that in the age of Big Brother and other reality TV programmes, the technology now exists - fingers crossed - to potentially show The Year of the Sex Olympics to a wider audience in its full colour glory; Nigel Kneale's original vision of a future where television had evolved to become a mass-market pacifier has never been more relevant.