Gomez, Thanks for your reply.
I received an E-mail direct from UKTV which covers Drama which states:-
In regards to your enquiry Like most channels, we don't send flags to denote exactly when a programme starts and finishes as this would go off the timings on your equipment. We would advise you to use padding to guarantee full recording and a lot of recorders will have this automatically built in or an option to do so.
Each day is timed separately as each individual programme is not exactly the same length, so the billed times we supply are to the closest 5 minutes - the time the programme starts and ends is never exactly the time stated in any programme guide and Ofcom allow every broadcaster to start a programme 2 minutes either side of the stated time. So, for example the programme afterwards is seen on the EPG to start at 1500pm, when in reality its starts at 1502 and the preceding programme finishes at 1500.
The tolerance of the your recording box needs to be adjusted to allow for an extra 2 minutes going forward and you should never miss another second.
Sometimes the case if a recorder is used to record multiple programmes at once, and doesn't use padding, that shows can be cut off from time to time. Although this can be quite common it is not a fault at our side of transmission.