tomatoes in hanging baskets

Tomatoes are self-fertile and the flowers should pollinate themselves, so setting fruit shouldn't be a problem. Are the fruitlets falling off? Flowers on tomatoes only last a few days.
There are special varieties for this, such as 'Tumbler'. Is this what you are growing? It's unlikely you will succeed with ordinary tomato varieties except with small cherry tomatoes.
If your baskets are in a sheltered spot there shouldn't be a problem but you need to water and feed a lot with hanging baskets.

Well we keep our tomatoes in a cold greenhouse as I doubt they would do well outdoors - though we had to watch them like hawks during the two week heat wave. It could well be it is too cool and damp and, as Bertie says, you need to use tumbler tomatoes as normal varieties are designed to grown upwards not hang.

Inreference to both answers.
these are Tumbler toms which are specifically for baskets or tubs
The flowers have been there for weeks and no fruit has appeared. It could be the weather has changed and its just not warm enough. But our son who lives nearer the East coast has exactly the same result.

I can only say where we live (Moray coast) it is always a bit of a risk growing tomatoes. The fruit is never ripe until September - unless you grow in a heated greenhouse...