This practice has now apparently largely ceased, due perhaps to the decline of the light orchestra as an institution and maybe also to the decline of the usage, once common, of performing extracts from larger works in live concerts. I do not claim, of course, that Elgar was unique in this. But it is worth making the point that Elgar was surely alive to the possibility of marketing lighter music even when he was preoccupied with something more 'serious'. It is said, as a generalisation. that Elgar wrote, or at any rate, completed, nothing after producing the Cello Concerto in 1919. The inter-war years were the heyday of British light music, most of it gorgeously tuneful and beautifully scored, not to mention British light music institutions.
Information is inevitably patchy.
We know that he admired Edward German's music and told him so. But German produced many serious compositions, symphonies and the like, and like Sullivan before him, aspired to be a serious composer even though he was fated to be better known for his lighter work. I suspect that it was the German of the operettas and the incidental music as these were then so much more accessible, as they are still. We may cite a few examples of this. Wood's own Variations on a Once Popular Humorous Song , incidentally, have some very Elgarian moments.