I think that the 1924 date may apply to some of the parts used to build that special, but it's obviously of much more recent construction.
The French site where the photo can be found is a bit dodgy on describing non-French cars and "Sport Racer" must mean something in French that is different from the English - we would not describe a single-seater as "Sports racer".
I see they have taken a lot of Lea-Francis photos from our Owners' Club website but with minimalist (and not necessarily correct) descriptions even though we give lots of information. I think that site should only be used with caution.