Ah, I may be getting confused about this. It was Aznavour's own version that got into the charts, but now you mention it I think it was Skellern's version on the TV series.
I'm confused about this one as well! The Scaffold are credited with composing and performing the theme tune that was used on the TV series, but the lyrics on the commercially released version are completely different from the ones on the TV series, and the musical arrangement is different too (though they both use the same traditional tune). The version that was played on the show last week was never to my knowledge used in the TV series. Unlike the version that was played, the TV lyrics were directly relevant to the characters:Not sure about "The Liver Birds", but probably the lyrics on the TV version were more 'Suitable' for a SIt-Com.
"What's got four legs, walks peculiar
Talks with all the choicest words
What's got four arms, loves to grab you
Answer is two Liver Birds.
If you're standing on the corner
All alone and feeling low
Liver Birds'll come and grab you
Singing ee i ad ee o"
Plus the memorable exchange (spoken during the closing sequence):