Hello Kate, I started using Schultz's Houseplant Garden Insect Spray.
Hope this abbreviated version takes you to the page.
http://tinyurl.com/2okah4

I see you are in England so not sure if you can get the stuff. It is
manufactured in Germany,
so maybe.
NB....There are a few types of spray that look the same so be sure to check
the ingredients
It must have Pyretherins .01% ,
Hard to believe but it really works but of course you have to keep at it.
Cheers Wendy
"Kate" wrote in message
...
Up until now, I have been removing these fluffy, white things with a
wet paint brush. Obviously removal hasn`t been complete, as they are
now gathering in the joints on a flower stem. Can I use a paint brush
dipped in, for example, isopropyl, to kill them, please, without
damaging the plant?

Many thanks
Kate