… for some reason have more bicycles stored outside compared to other tube stations I see.

I do wonder why, there is not many offices or the like near by to be the reason for it. And if people do cycle to work, why stop there ?

The City is around a mile away, Holborn is 2 miles away and Charing Cross is 3 and a bit miles away, which will not take very long on your bike.

Getting of your bike, locking it up, walking down to the platform at Benthal Green station, wait for train (along with 100+ other), getting on a train that is full to the brink, standing up for say 1-3 stations, get out out station, walk to your work place. Would take much longer and would be nastier than riding your bike for the last mile or so to your work.

It beats me, why ?