If you don't know Novello's musicals - and who does, these days? - you'll know his gloriously inspiring patriotic First World War song "Keep the Home Fires Burning" (while your hearts are yearning), and the irresistibly nostalgic "We'll Gather Lilacs" (in the spring again, and walk together down a country lane); it was thrilling to hear, after so many years, such great melodic light opera numbers as "Some Day My Heart Will Awake" from King's Rhapsody and "My Dearest Dear" from The Dancing Years.
The Dancing Years, aka "The Prancing Queers", is the only Novello show I've ever seen, in a rather tatty touring version by John Hanson (who died in 1988), but the songs have never left me; it was probably the last Novello musical professionally performed in this country... until the Finborough revived Gay's The Word last month. The chorus included Paul Kerryson, now artistic director of The Curve in Leicester, and, as it happens, my younger brother.
Item after item at the Proms reminded us of just how beautifully Novello constructed his songs, in great melodic arcs, quite demanding of the singer's register, bursting with sentiment and never a hint of cynicism or bitterness. And as Callow reminded us (in a commentary written by Paul Ibell), The Dancing Years (1939) was actually quite a controversial musical, evoking the Nazi threat to pre-war Europe at a time when the British government was bent on a course of appeasement with Hitler.
Callow made an amusing historical parallel, too, with reference to King's Rhapsody (1949), in which a blonde princess, married to the heir apparent, is rejected by him in favour of a much older, and longer-standing, mistress.
The Halle submitted totally to the lushness of the music, and the singers, Bevan especially, who has a wonderfully rich soprano with contralto elements and beautiful purity at the very top, sang without condescension or fustiness; they really did almost manage to bury the old Radio 2 "Friday Night Is Music Night" stigma of this stuff.
For Novello comes at the end of a tradition of European light opera that harks back to Franz (The Merry Widow) Lehar and Sigmund (The Desert Song) Romberg. His shows were glamorous spectacles, exercises in sheer escapism, crowd-pleasing entertainments.
And he was at least as big a star in the English theatre as Noel Coward, even though he was Welsh. Sandy Wilson, the composer of The Boy Friend, who admired Novello enormously and wrote a superb (and superbly illustrated) book about him in 1975, said that he embodied all the romantic ideals of his age: the Latin Lover, the Sheik of Araby and the Vagabond King.
Dark and dashing, a bit like a mixture of Tyrone Power and Rudolph Valentino, Novello's features also possesed, says Wilson, "in the modelling of the mouth and the flare of the nostrils, a dash of the Byronic aristocrat combined with the more aesthetic breed of royalty - Ludwig of Bavaria, say, or Richard of Bordeaux."
Callow touched on these facets, as well as the minor blip of contravening a petrol rationing law during the Second World War and finding himself in prison for a month (the offence would usually have carried a £50 fine but, said Simon, he was clearly a victim of rampant homophobia, suffering a similar humiliation to John Gielgud's a few years later when caught cottaging).
The amazing thing is that, although he usually starred in all his musicals, Novello never actually sang himself. (John Hanson did, unfortunately, and dyed his hair, too, as Ivor did in later life.) And he was renowned for his social life which featured many old theatrical ladies, two grand pianos and a bevy of beautiful boys. "It's...it's...like...fairyland!" exclaimed a bewildered Margaret Rutherford on attending one of Ivor's parties in the flat he kept at the top of the theatre which now bears his name.
Callow told us how Ivor wrote his box office receipts on the dressing room mirror each night in red lipstick. And how one of his wittier not-so-loyal ladies, Dame Lillian Braithwaite, responded to the chuckle of her companion at a first night as the orchestra struck up the first big tune - "Oh, naughty Ivor, that's an old Welsh hymn" - with the tart remark, "Which is more than one can say of the composer."
The Finborough's Gay's The Word (1950), with lyrics by Alan Melville - Novello rarely wrote lyrics; most of them were written by the poet Christopher Hassall - had a mixed reception, though there is talk of further performances; and I know that Cameron Mackintosh considers the great popular musicals completely impossible to revive nowadays.
But last night's Prom made a very good case for some kind of theatrical extension, perhaps in a longer concert format, perhaps with a brand new book incorporating the best songs in a modern staight-faced context, though it's hard to imagine what that might be.
Whatever happens, last night's treat was more of a revelation than a wallow, although there was only one song - "Pray for Me," an intensely affecting farewell from the composer to his closest friends, Ivor's last song, beautifully rendered by Toby Spence - that I didn't know at all.
Not for the first time in the evening, you realised that there has been only one true successor to Novello in terms of melodic power, unabashed romanticism and theatrical dynamism, and that is Andrew Lloyd Webber. So perhaps we'll have that long overdue Prom devoted to his music next year...