It's you again!
From my limited experience of just over a week using the Sony 870 I've had programmes that start late and finish both early and late.......one extended by over half an hour and took in News at Ten. The boxing cut off half way through the last round.
I tried twice to set the machine to record Wire In The Blood prior to the day of the event and each time the info was lost sometime overnight.
I finally succeeded on the day of the event!
All the above timed recordings were attempted using the EPG on freeview and maintaining the EPG link which presumably is meant to take account of delayed starts etc.
It seems there is some way to go before it's any better than the trusty VCR abs VideoPlus.