Is it the heat

Some varieties of tomato probably do better than others in hot, sunny conditions.
We are growing Gardener's Delight and have been picking them for about a week. In the greenhouse, they are ripening the same as in previous years. My husband has actually increased the sun they get by removing some leaves.

The tomatoes growing outdoors are almost ready to eat too.

I would remove a lot of the leaves. This can encourage ripening, I think, though can limit the plants' ability to keep producing new tomatoes late into the season.

Just picked first ones yesterday

My tomatoes are large but still green. Just keep watering and caring for them. If at the end of the growing season they still aren't ripe, just cut them off while leaving a generous amount of stem on them, bring them in the house in a cardboard box and they will ripen.

mine are in a small plastic greenhouse from Lidl , I emptied the grow bags into a trough and put one and a half in , and two Gardeners Delight , they are cropping really well . I have two cucumber plants from the Lidl wee seed pots and have had several cucumbers from them , growing in the same type of trough as the tomatoes

My Alicante, outside in a grow bag, have made wonderful growth but the tomatoes are still small, cherry tom sized. They are swelling, but very slowly. The Gardeners Delight in pots don’t have much on them at all - but loads of leaf. I don’t think its going to be a good tom year for me!

I was away last week and the tomatoes got less care , but they were all starting to ripen when I got home , maybe less water now , pinch out the top , cut off the bottom leaves and that will get them ripening

Ours are ripening now. I picked the first ones at the beginning of the week. DH was on the verge of chucking them out, but now he's watering them and has tied them up.

I've already had a good few from my three plants, but have just remembered that they are shaded a fair part of the day.

Assuming they’re in a greenhouse, you can put a banana under them. It hastens ripening.

thank you.

Carry on watering and feeding them. My tomatoes are behind this year but I'm sure they'll catch up eventually.

I had the same problem one year and I carried on watering and feeding until about October then picked them all and made green tomato chutney and gave lots to friends and neighbours.