Thank you for taking the time to respond with your good ideas.
Here's what I did.
Saturday I grated about two thirds of them, and added a third of a cabbage and a carrot. A massive dollop of mayo, a plop of mustard and it was good to go.
Actually, it tasted much better the next day when everything and seeped in together.
Thanks Frugal in Norfolk -great idea!
Still a third of the radishes left to go. I contemplated The Minnow Diaries idea of roasting them, and went with that, but instead put them on top of a home made pizza.
I am a bit fed up of radishes to be honest now and have to eat the rest tomorrow.
I still have about 5 radishes left. Sod the frugal life, I am throwing them away and not buying a radish again for a long long time.