[Anton]

I have 10 crimson beefsteak tomato plants and five crimson crush growing in the attic (out of 10 crimson crush seeds, only five came up and they are not very robust-looking.
Anyhow, one of the beefsteak plants has suddenly developed some funny leaves (see photo). Any idea what this may be please? I hope the gnats I see don't have anything to do with it. The other plants are OK as far as I can see.

Anton

[New shoot]

That looks more like heat or weather damage to me.  Maybe caused by very strong sunlight or strong chilly winds.

They should recover from that.

[Anton]

Thanks for the reply. Thanks for putting my mind at rest. Maybe strong sunlight but no strong chilly winds in the attic.

Anton