Train crossed ML to RL back to ML back to RL on gwml

[Jamiescott1]

The 2208 departure from Paddington to Didcot is scheduled to run on the main line to dolphin junction where it changes to relief line to didcot

Last night it changed to relief line at West Drayton where it crawled behind an EL service to dolphin junction where it changed back to main line. It then proceeded along main line where it changed back to relief line before maidenhead.
Ending up running late running and missing the connections with Thames Valley branches (65 minute wait at maidenhead for the next marlow branch train)

I cant see any other trains at this time changing lines.
Any explanation behind the signallers decision ?

 

[30907]

At least the preceding 3 trains did this per RTT, which suggests a temporary signalling issue on the Down Main.

Not holding the branch trains at that time of night seems poor.

 

[Jamiescott1]

At least the preceding 3 trains did this per RTT, which suggests a temporary signalling issue on the Down Main.

Not holding the branch trains at that time of night seems poor.

Thanks,I didn't spot that.
Not sure if the drivers change for the last branch line services of the day which may explain why the penultimate trains didn't wait.