chillis are very simaler to tomatoes and this might be a mith but lots of people do this
me being one
TOMATOES: Tomato flowers have both male and female organs and are self-fertilizing. Pollen is shed in
greatest abundance between 10 am and 4 pm on dry sunny days. Normally the wind will pollinate sufficiently.
Optimum fruit set occurs within a narrow range of night temperatures, 60-70?F. When night temperatures
drop below 55? or rise above 75?, interference with the growth of pollen tubes prevents normal fertilization.
The pollen may even become sterile, causing blossoms to drop. High daytime temperatures, rain, or
prolonged periods of high humidity also hamper good fruit set. If the humidity is too low, the pollen will be too
dry and will not adhere to the stigma. But if the humidity is too high, the pollen will not shed from the stamens.
You can't control the weather but there are things you can do that will help. To aid pollination, gently shake or
vibrate the entire tomato plant. Do this at midday when temperatures are warm and humidity is somewhat
low. If you have only a few plants, you can hand pollinate with a Q-tip or small, soft paintbrush, moving from
flower to flower.
PEPPERS and EGGPLANT experience pollination problems similar to tomatoes.
when most chilli plants flower when growing outdoors day temps will be as above well should be uk summers? lol
and i do as sns said with a cotton bud no need to shake the plant
all the best
paul