Well for once the Beeb didn't over-egg it, and admitted that it wasn't a safety issue. Makes a welcome change to see a sensible piece of reporting.
When a train divides there's always a long delay because you're not allowed to couple it back up until an RST (Rolling Stock Technician) has examined both trains. So the line is blocked whilst the bloke makes his way across Rush-Hour London in a van. At least now that the slam door stock has gone there's no jumper cables or air fittings to repair. On modern EMUs all normal services go through the junction boxes located underneath the couplers.
I don't know what stock it was, presumably 375 ? I do remember that a while ago Networkers went through a phase of coming apart. Connex changed the couple-up procedure by adding a 5 second push on-test to the existing 5 second pull-away test. It did the trick. (Of course they have crappy old tightlocks, whereas I believe the 375s have all been converted to Delners which are supposed to be far superior). Time will tell no doubt.