A bit of a heads up for y'all.
B and Q do a 3 brush set for £2.48. Now, it's an
abrasive Stanley brush set and contains one nylon brush, one brass brush and one small wire brush.
I do not condone the use of wire brushes on crags/boulders, but the nylon one is about as stiff as an M16 so it's a good deal if you happen to want this and 2 others for DIY. Although obviously it isn't a double ended effort.
Anyway, just in case you want something cheap and chearful to add to your brush collections.