Hi Italophile, I know what you mean, but they were in a place with loads of light. What I suspected was that they'd bolted, which is what's happened to me in the past when I've sown them outside and we've suddenly had hot weather. We had temps of 26ºC-28ºC in March for two or three weeks just after I'd sowed them. They are 'boltardy' though which I thought didn't bolt, or at least not as quickly as other varieties.
They're still in the modules where I sowed them, so I haven't separated them yet, and wasn't planning to.
What do you think? Shall I still plant them out?