It must be that if you have a can of aerosol paint in your hand you will be compelled to just spray whatever is to hand.
I say this because the pedestrian access that leads from Lower Marsh end of Leake Street into the tunnel section itself is covered completely with what looks to me like a complete random mess. I could understand if people were testing out new skills, but this just looks like some kind of free-for-all; the proverbial 'explosion in a paint factory'.
Leake Street is a dedicated space for graffiti and street art and there doesn't appear to be an inch of bare brick visible any more – even the railings and crash barriers have been 'decorated'. And, as I have reported here before, the old market barrows in Lower Marsh have been tagged too even though they are not part of Leake Street's walls or fixed furniture (grr!).

I peered down from ground level above the pedestrian tunnel and saw a group of people spraying a wall in the Station Approach section. The smell of the propellent wafting up to me made me want gag – how do people actually walk through the tunnel?!
As per Parkland Walk, the quality of the work, to my eye (and nose), isn't up to much.
Street art? Really?