Hi,
I've had my first flush from a batch of mushrooms but now I've noticed some blue stuff on the side of the cake. At first I thought it was just bruising but I'm worried it may be mould. I've enclosed a couple of photos. If anyone has any thoughts on what it is and what to do I would appreciate it. Thanks.

This is 100% infected, not just bruising.
Your cake looks quite spent too and it often happens they get infected as the mycelium gets weaker.

Throw it out but not in your growroom as not to increase the mold spore load in the air.
Also, don't breathe in the spores.

Definitely looks like contamination. to find out for sure, take a q-tip or paper towel and wipe the discolored section. If it can be wiped off, it's definitely mold.

This is mould. Looks like trichoderma to me, very common type of mould.

Discard this immediately as far from the growing area. This can easily contaminate the whole space. Also thoroughly disinfect the sorroundings (I use 10% bleach).

Thanks. Will do xx

For future reference, bruising is distinctly blue. Sorry about the loss of your cake. After a while, you will be able to spot trich before it goes to spore. It grows differently and has a different look than the mycelium it will take over. I've had half a dozen cakes push one good flush followed by pinning for another and then that evil green set in.

throw it in some compost. sometimes fruits will form, given enough moisture and mild temps.