Tomato plants wilted in a day!

All of my tomato plants were fine last night when I checked on them. Watered them with tomato feed from underneath before bed and today I've got home to find them all looking like the attached picture. About 20 look like this and 3 are still OK.
Have no idea what happened in the space of a day - they're in the greenhouse and it's been sunny all day. Soil/compost is damp so they're not underwatered and there is no evidence of bugs or anything. Nurtured these for months so very disappointing. Any ideas what went wrong?

 

Greenhouse just got too hot today maybe? Hopefully they will recover by morning. A bit scruffy maybe but alright again

 

It’s a bit early to be feeding them. Generally start feeding when the first fruit set. However, I’m can’t say for certain that feeding them too early has caused this to happen

 

I put some healthy cuttings of fuschias, brocolli and cabbage in the same greenhouse and after 1 day theyve wilted too. Can only assume its getting too hot.

 

Try putting a thermometer in there, it will give you a better idea how fast these things heat up on a sunny day.

 

The last few days have really ramped up the temperatures. In my greenhouse it got to about 43 and that is with all automatic roof vents fully open, louvres left open and doors opened first thing in the morning. I have ordered some 40% shading material now!

 

Yes, my guess is that it got too hot in there. At the moment, I’m heating at night, and opening up during the day. Always a bit of a problem this time of year, with the massive fluctuations in temperature.

 

Yea just too hot, thankfully my greenhouse is really old, missing several panes and the door wont close, so it doesnt get too hot in there anyway