[Rich72]

I have absolutely hundreds of flowers on my french bean plants and there are always bees and flies buzzing round them. Unfortunately, out of all the flowers I have managed to harvest the grand total of .......1 bean. Am I doing something wrong? the flowers just seem to drop off without a bean.

[stompy]

Is the weather hot and dry where you are?
lack of water can cause poor flower set.
Give them a spray with water, on the flowers too, this should help.

[Jay The Digger]

French beans will drop their flowers if they are not kept constanly moist around their roots.  That is why a lot of people dig a bean trench and fill it with well rotted moisture retentive material.  Even newspaper is good.

I personally have never used a trench.  At the base of each pole where the bean plant is sited, I position a cut off lemonade bottle so it is touching the rootball and fill this to water.  Another trick I use is to allow the plants when young to form a clump before guiding up the poles.  This allows some shade around the base to stop it drying out as much. 

In very hot weather I spray the flowers in the evening with a water mist. 

[Rich72]

it has been very warm for the last couple of weeks but i do water them almost daily. It has occasionally been quite windy too, will this blow the flowers off?

[sunshineband]

French beans pollinate themselves without the use of bees etc, so it is more likely to be environmenatl conditions like Jay & Stompy suggest