Haywards Heath station question

[Skimpot flyer]

I was on the 10:02 Brighton to London Bridge this morning, after the 09:58 and 10:18 services to London Victoria were cancelled. I heard mention of a 'failed train' somewhere up the line. To my surprise, my train crossed to the down line just before Haywards Heath, and the pulled in to the easternmost of the four platforms, on the down side of the station. I could see a failed 442 Gatwick Express in the westernmost platform, and a Victoria-bound train on the other platform face, on the up side. How unusual is this use of 'wrong line' running?

 

[MrB]

Not sure how unusual it is but from memory the BML is geared up for fully bi-directional signalling from Haywards Heath down to Brighton.

 

[Sunset route]

The up and down loops are fully reversible and are often used against the normal direction of flow to get trains around problems or to regulate around other services, they do not form any part of the bi-directional signalling. For the record there is Simbids between Preston Park-Wivelsfield-Haywards Heath and full bi-direction Signalling between Copyhold Junction and Balcombe Tunnel Juction (converted from Simbids last year)

Simbids = SIMple BI-Diectional Signalling.