What instrument is used to make the cascading whistle sounds during and at the end of Fun It?
I know it is not a synthesiser but my brother doesn't believe me.
They were from an early electronic drum called Syndrums. Roger had them off to the right of his kit near his ride cymbal in live shows. He had a set of four of them and they were also used during Death on Two Legs at gigs as well. If you look at the photo in the studio on JAZZ you can see four small padded circular drums on a stand.
Sebastian is correct! Syndrums came out sometime in the 70's. It's like a small drum pad with a cord connected to a box where it plugs into and from there you can get what weird sounds you want. Listen to Live Killers at the begining of Death on Two Legs. Roger uses them at the front of the song. Electronic drums have come very far since then unfortunately.