Anybody know about tomato purple leaf disorder?

Will try for a photo.....

AlieOxon Tomato seedlings are prone to turning purple underneath,sometimes due to a drop in temperature in growing conditions.Can stunt the growth of the seedlings sometimes,hope this helps.I work in a nursery where we grow thousands of tomato plants of various varieties.

Thing is, last year the greenhouse plants got to about 2ft high and then went purple and the growth slowed - this when the weather was warmer.

Now the seedlings look the same. They've been on a windowsill.
Also I had a solanum creeper which went purple and didn't grow.

Picture? won't post.

Too cold or in a draught

I might accept that about the seedlings, except that they've been in the house.

But something happened to my half grown tomato plants last year that I have never seen before. and come to think of it I have been growing tomatoes for most of the last 30 years.

See
www.growingproduce.com/crop-protection/disease-control/tackling-tomato-purple-leaf-disorder/

DH- very experienced gardener and tomato grower-says he doesn't know but would check RHS website for an answer. . . .

Tomatoes are the most popular plant for the veg. patch in our area (SW France).
Many different sizes and colours. But grown outside from seed, or small plants from the garden centres and markets.
No mention on the french gardening forum of purple leaf . The main problem here is blight, and that attacks the leaves first. It's caused by a fungus, which could be more prevalent in greenhouse conditions. We've had it a couple of times (on potatoes too, plus colorado beetle .

I grow my toms in the greenhouse since, a while ago, I lost a whole crop one year to blight.

As a child I remember posters in the post office telling people to report Colorado beetle.....haven't heard of it for years here.

Trying different compost for potting on....the are growing but still purple.
My sister would write, but RHS want details, like what compost I used last year, and I have no idea now!

Tomatoes are the most popular plant for the veg. peoples.