On 10 Oct, 11:18, wrote:
When I regularly travelled on that route, the problem used to mainly
be dwell times at Blackfriars, and access to London Bridge, which I
believe is just 2 tracks (1 up, 1 down) at one point. 15 minutes
between the 2 stations was not uncommon. Someone at Thameslink told me
an additional problem was that Southern trains 'had priority over
Thameslink trains at London Bridge' as it was 'their station', which I
was a bit dubious about.

I've been on Thameslink trains between Blackfriars and London Bridge
which have been at a standstill, and the driver has announced,
"Apologies for the delay, we are being held up as the South Eastern
trains are being given priority YET AGAIN". May be perception rather
than reality...

Patrick