Those looking to buy a bike in London "basically stuffed" at the moment

Mechanics are certainly working overtime. I was in my regular LBS a couple of days ago and overheard them taking a call from someone wanting a service. They booked him in for November.  Today, I bumped into a neighbour taking his kid's bike down to the local (crap) bike shop because the gears were jumping about a bit.  I saw him again later and asked if they'd sorted it. They'd told him to come back in October.  I got it up on the workstand and had it sorted in a couple of minutes.  

I don't see many people on bikes dragged out of the shed, almost everyone is on a new toy, with garish clothing and the de rigeur badly fitting helmet, more often than not cycling on the pavement and with absolutely no roadcraft whatsoever.

I can't imagine it's a very good place for suppliers throughout the chain to be in either, there's still huge sums of money tied up on a perceived uplift that may last until 2021, or not.

The harsh reality is that with a nascent direct supply chain in the UK, with the majority of orders being fulfilled from the other side of the world, stock levels will remain tight for the foreseeable future.

I wouldn't gamble my own money on a huge shift in cycling numbers, especially with winter around the corner and at a minimum, local lockdowns rising/continuing.

I doubt wholesalers and retailers will either.

What does this 'permitted exercise option' mean? What forms of exercise have been banned?

This is good news. Covid-19 is horrible, but at least the enormous grey cloud of lockdown has just a hint of a silver lining: Lots of people are getting out on their bikes.

Not the road.cc regulars; we were already regular riders and most folk commenting below the line have a couple of bikes and no trouble doing their own tweaks or ordering parts online. (My Wiggle spending has gone through the roof). The big change is for normal people, folk who might have had a rusty old £100 Halfords special in the shed, they dragged it out into the daylight earlier in 2020 when the lockdown started, and since then they've decided to either fix it up or replace it, and they're more dependent on an LBS than we are. They probably outnumber the regular riders, and it's amazing that they're getting on their bikes. Mechanics might be overworked at the moment (we'll find a new equilibrium) but this trend is good for public health and good for mobility.

This isn't a London problem. The difficulty in buying a new bike exists pretty much all over the country. Bike shops get their stock usually from the same suppliers, who are usually authorised wholesalers of particular brands, any orders have to go via them. I know of one high end brand, when my bike shop owner friend has logged on to order some bikes from them, is being given a lead time of the middle of 2021.

This is what happens when companies don't hold stock and rely on 3 month lead times from China

I've been chasing upgrade parts for my bike, having spent around five weeks trying to source anything that wasn't a BSO. Very little stock in the UK of anything that isn't Ultegra/XT level or above so I've ended up getting parts from Germany. Spoke to my LBS mechanics about this and they're running first come first served with a seven day turnaround on anything more than cable tweaks, punctures, or new chains. If they ran bookings they reckon they'd have slots available just before Christmas. And 2021 stock is very slow to arrive. Might be worth getting Madison's view on parts shortages in the UK.