Examples of skip stop/express services on the Tube (or DLR & LO too)

[Rogmi]

Brent (now Brent Cross) had outer fast tracks to allow the station to be skipped NB and SB. This appears to have been in place when the line was extended from Golders Green towards Edgware and the additional stations all had 9-car platforms (except Edgware!). I don't know how often it was used, but if full speed was allowed passing the station, it would certainly cut some time off the NB journey as it's a good downhill run from GG.

The Northern line originally had passing loops on the Edgware extension from Golders Green. As I recall, when the trains were lengthened to 9 cars, the loops weren't long enough, especially when coupled with the platform extensions, so the loops were removed. The primary example was at Brent (now Brent Cross) tube station.

I've seen photos of them before, but can't seem to find any online. You can however see the loops very clearly on old OS maps:

View map: Ordnance Survey, Middlesex XI.11 (Hendon) - Ordnance Survey 25 inch England and Wales, 1841-1952

The space where they were is also very obvious at the station today.

I posted about Brent before I saw this post (I didn't realise there was a page 2 of the thread!)
As far as I'm aware, Brent was the only station that ever had passing loops on the Edgware extension. Somewhere I have the equivalent of the 'Yellow Peril' for when the extension towards Edgware was opened, and Brent was the only station with the loops shown. Because Brent was originally a 9-car platform, then this shouldn't have been a problem for passing trains. The island platform was later shortened, although the NB starter still remained in it's original position.

Covent Garden (Piccadilly Line)was skipped except when the market was trading I think

When I was on the Picc line in the 70s, Covent Garden was always closed (at weekends or just Sundays?). I think it only reopened properly when the market became a tourist destination.

Mornington Crescent was also closed weekends and Bank Holidays until business picked up (and became a convenient alterntive to Camden Market to relieve pressure at Camden Town). MC was the only station on the Northern line in later times where it was permitted to run through the station higher than the official 5mph (20mph as I recall), partly due to the longer overlap on the starter. However, unless cleared in advance by the regulator, the starters were speed controlled and around 15mph was usually the maximum possible.

 

[mr_jrt]

You are quite correct - only Brent ever had them. I recall standing on the platforms as a child along that stretch and wondering if there was a removed track at a few of the other stations though. I now know there wasn't, but you have to wonder if there might have been a bit of the old passive provision in play, perhaps. Hendon Central's cutting and bridges are wide enough for outer tracks (though you would probably need two additional tunnel bores!), and Colindale has an unused span on the southbound side, as does Burnt Oak. One can but wonder if they would have been used to speed up southbound trains had the line been extended beyond Edgware, as once intended.