Of course, there's the wonderful Morecombe and Wise sketch - a triple act not a double act - which is no small thing when performing alongside the UK's best ever comedy duo. For me it's a toss up between that and "four candles" so it's something he could rightly be proud of
But more seriously, I have a lot of CDs with him conducting (usually the LSO), and they are invariably exciting and amongst the best available take on a great deal of music. If you don't know a specific version of something and what version to get of an unfamiliar composer, you rarely go far wrong with Mr Preview and the boys in the band
Doing a bit of googling, noted that he wrote an opera of Streecar Named Desire. Maybe worth a go ?
Also didn't realise he'd (EDIT arranged (not written) the music for My Fair Lady - for which he got an Oscar - one of four wins and many more nominations.
He was a serious jazz pianist as well