The composer of Mr Benn Duncan Lamont explains some of the background in the CD notes to As If By Magic (Jellymould Jazz, ****)

The Lamont 17-piece big band meanwhile negotiates the changes and relaxes into the music. His style is a jazzier Ronnie Hazlehurst in the context of 1970s television composers of the day, the influence on the Lamont writing style of John Dankworth also evident more to the point as the album progresses especially regarding the jazz context which is the crucial thing. This might, after all, be considered feelgood modern mainstream, hush-puppy friendly soft shoe shuffle-like jazz in flavour, the sort of style that the Bull’s Head pub in Barnes has championed over many years. It does not jazzify the original music, it merely draws out a few hints and develops them a bit, the magic as jazz a thing as the show itself. Also because it is the composer’s own band using his charts the subtleties are not lost by another arranger who might also understandably have wanted to have put their own stamp on it.
For Kenny Wheeler fans there are three tracks on the album featuring Wheeler on flugel. He had appeared on the original sessions for the television show many years ago as well. Alistair White in the four trombone section is one of my picks of the soloists, the other is Martin Shaw, on trumpet, who is so poignant and fragile on ‘The Dragon's Tale.’
Lamont’s skill in arranging the music is to strip away the glare without making it at all bland and he uses natural textures such as that of the woody resources of the marimba again swinging it a little more than the original but in not too generic a way. David McKee who wrote and illustrated Mr Benn, which first ran on TV in 1971 and 1972 and who facilitated the making of the album by funding it, says in the notes: “From the beginning the music was always an important part of the films and when the films were finished it still remained important to me.”  
A clip above indicative of the Mr Benn TV incidental music might jog your memory especially if you were a Blue Peter and Jackanory-watching child in the 1970s who may very well also have loved the series. The voice of the narrator you can also hear. As if by Magic itself is utterly charming, a reward for your crucial sense of curiosity and somehow still, child-like sense of wonder.