Signalling problems on UP slow line into Waterloo

[ctom_s]

Several times over the last few months (at least 5 times that I can count, all at off-peak times - peak seems fine, although presumably there are more) there have been signalling problems (or at least that's what the announcements say) on the UP slow into Waterloo. This has meant trains were running fast from Woking or Surbiton into Waterloo, even skipping Clapham Junction. Each time I was told to go to Waterloo and come back out again.

Does anyone know what is happening and why it's a recurring problem?

This happened again today (1411 from Surbiton ran fast to Waterloo), although I then got on a train 5 minutes later (delayed 1401) which stopped all stations so I'm not convinced it was a genuine signalling issue.

 

[Big Jumby 74]

If there is a signal problem on the Up Main Slow, depending on the circumstances they made need to thin out the service on that line to prevent a back log, so a proportion of SL services may be diverted via the Up Main Fast, and hence omit some stops.

 

[Kite159]

Especially Clapham Junction as the loop to access platform 7 is a lot slower compared to platform 10.

 

[Horizon22]

As an aside announcing the “Up Slow” is fairly bad. Unnecessarily railway jargon for passenger-facing communications which the vast majority of people won’t understand.

 

[E16 Cyclist]

It’s not the up slow that’s the problem it’s typically the up fast and stopping services need to be sped up to allow fast services to use the slow lines and not have everything tripping over each other

 

[ctom_s]

To be fair, UP slow was my usage it wasn't in the announcement. So from what I'm hearing there's no real recurring specific issue it's just something in the standard practice toolbox when things aren't going right?