In article ,
bugbear
_trim says...
I recently noticed that a brooks professional saddle
on (cough) one of my machines in my garage
has gone bright green with some kind of low-profile
mould.

Bugger.

The saddle is rather soft and damp.
I've removed it and bought it indoors for some
TLC.

Has any seen this before?

Yes.

Is it fatal?

Probably not.

Any treatments known?

First slacken the tension adjuster. To clean it up give it a good scrub
with saddle soap then let it dry (far corner of the airing cupboard
rather than top of a radiator). When it's bone dry apply lashings of
Proofide and leave to soak in for a while before buffing off the excess.
Re-adjust the tension.