UKC

I usually climb on the Avon Gorge side, but whilst looking for some suitable top-roping to take some beginners to (with easy access from above for rigging), I've explored Quarry 1 & Quarry 2 on the Leigh Woods side. There are some great routes there but quite a few seem very overgrown since they were last climbed or photographed for the guidebook - is the clearance of brambles & ivy acceptable here?

Leigh Woods

I'm aware of the local SSI rules (don't disturb the local Whitbeam / Speedwell etc)

Shouldn't you be asking the National Trust (who I understand own the land) rather than UKC?

Yeah fired off an email to them already, just wondering what has been done in the past. I presume when access was initially negotiated, some small amount of clearance was permitted so I'd only be repeating what has been done before.

Leigh Woods is riddled with ticks at the  best of times (May-Sept), so be aware that by clearing scrub, you’ll no doubt get covered in them! 
 

Not all the quarries are owned by the national trust: quarry 3 isn't an 1 and 2 are wills estate i believe. Think there's more information in the avon guide

Forgive me if I'm wrong but I was under the impression that clearing ivy etc. at certain times of year (anywhere) was not ideal, as it's important habitat for birds and bats etc. Given that we're into the 'sweet spot' of nesting times now, I'd maybe avoid any extensive cleaning at the moment. 

Absolutely. Don't do ANYTHING until August at the earliest

I'd advise not doing anything until you have heard from the Trust who may need the legal consent of Natural England in order to sanction any scrub clearance. Maybe go through the area BMC rep  too?  There's a wide range of species/habitats and features mentioned in the site citation and climbing is mentioned as an activity that may need management. 

Is it worth it? There is an undeveloped quarry that I know of that is covered in vegetation. The ecological damage to unearth climbs of unkown quality would be extensive, plus the damage from creating paths to the base of the climbs. Some things are best left to nature

I think it’s obvious that if you are on a route then snipping away an intrusive bramble is not problematic.

However it has taken your BMC reps years to build solid relationships with the National Trust and Natural England. So extensive clearance of vegetation needs negotiation well in advance and has to happen during the winter months.

Fir Tree Slabs offers some nice quiet top-roping opportunities.