Henry Jekyll (Bernard Bresslaw) works as a chemist in a shop run by his brother Victor (Jon Pertwee) and his sister Henrietta (Maudie Edwards) but they tend to look down on him - though figuratively rather than literally, as he is very tall. Take tonight when he attends the local dance hall and has to stand in for an absent formation dancer, as his brother takes to the stage to conduct his band: the result is disaster as Henry's complete lack of co-ordination and talent has him ruin the entire number. One girl, Snouty (Jean Muir), harbours a crush on him despite his clumsy ways, but this nice guy is always going to finish last... until he takes a leaf out of the book of his famous relation.
It's odd that Hammer, despite their reputation for bringing the classics of horror literature to the screen, never committed to a straightforward version of Robert Louis Stevenson's celebrated tale Doctor Jekyll and Mister Hyde: after The Ugly Duckling, they made The Two Faces of Dr. Jekyll where the ugly doctor turns into a handsome Hyde, and even more extreme, Dr Jekyll and Sister Hyde, where he underwent a sex change under the effects of his experimentation. This, however, was a comedy, seemingly as the vintage yarn was ripe for a parody version - you just had to ask Jerry Lewis about that, for his classic The Nutty Professor was curiously similar.
In the Lewis, he used the transformation into a dual personality to explore all sorts of psychological maladjustments and just plain eccentricities in a manner that laid bare his motivations and feelings about his screen persona. In The Ugly Duckling, Bernard Bresslaw did no such thing, so anyone wanting an examination of what made his character in the popular sitcom The Army Game tick would be in for disappointment. He did, on the other hand, get to use both his voices, the gormless, nice-but-dim one (higher pitched and more East End of London), and his proper actorly one (closer to his real voice, deeper and more serious), so in that way Lewis's range was matched.
Yet the Bresslaw movie was never going to supplant The Nutty Professor in the hearts of comedy fans even if it did get to the "nice guy idiot turns into smooth but nasty guy" plotline first, mainly for two reasons. First, it didn't go for soul searching in a range of expertly-produced and frequently surreal gags, and second, it was too damned difficult to see for decades, despite it being a Hammer production. Not every Hammer would be given the star treatment, but their horror or at least fantasy-based movies would be regulars on television and enjoyed lucrative repackaging after repackaging on home video releases; then there was a minor item like this that went so absent from the scene that many believed it to be lost until it showed up on British television in a very decent print in 2018.
That was the background, but how did it play? There were elements that fixed it right in 1959, such as the fixation on the dance halls as the main form of entertainment available, seemingly to all ages, judging by the range we see here, with Jess Conrad showing up not to sing but to essay the representative of surly youth. Also, such details as Henry's chief confidante as a gollywog he takes to bed with him is not something you imagine would be in a film from the twenty-first century, but the main plot about the transformed by potion Henry (into Teddy Hyde, an abbreviation of Edward and possibly an allusion to the Teddy Boys) taking part in a fairly complex robbery inspired by the French hit Rififi would not be too out of place in a modern comedy. Through it all, it was Bresslaw's show, though he had nice support from future Doctor Who Pertwee and Reginald Beckwith as a stooge, getting drinks spilled on him. No lost classic, certainly, but to catch it would scratch an itch for Hammer followers. Music by Douglas Gamley (listen for the sample of the Dracula score for the transformation scenes).