Silver leaf

My daughter has a little courtyard garden in London. After pruning her Bay tree somewhat hard last year, it has got what looks exactly like the pictures of silver leaf, and it has affected another bush as well. Should we start pruning to see if it is the fungal variety or false silver leaf, or wait a bit? Never seen it before.

 

It is a plant that can get silver leaf if cut back hard at the wrong time of year
http://www.bbc.co.uk/radio4/gqt/fsheets/09_09_01/fsheetsq6.shtml
unfortunately it doesn't say how to rectify the problem

 

http://www.crocus.co.uk/pestscards/silverleaf/

 

Oh dear! Pity she didn't notice sooner.