If the series has the 'Series Record' logo this avoids the problem, Unfortunately not all series or EPGs are set up for this.
My gripe at the moment is the BBC are starting programs early at times. You used to be able to rely on them to start on time but just recently Eastenders for example has been starting 2 or 3 minutes early. Last night it started at 19.28 instead of 19.30
If you look in the top corner of the screen you'll see two little white bars appear towards the end of a programme.
This is the signal for the VT engineer to start the new tape. Your VHS recorder is simply reading these to manage the recording. As you say, very useful, but no longer required with digital broadcast kit...
alan14: I am sorry, but that is incorrect. Yes, I have seen the marks you refer to, but they have nothing to do with controlling the VCR recording.
I have looked in the Panasonic instruction book and it is called "Programme Delivery Control", (PDC). It is a special signal transmitted, together with the normal TV signal, that ensures the recording will start and end precisely when the programme is transmitted.
I found this only worked on analogue BBC1 and BBC2, but never on ITV. I cannot recall what happened on channels 4 and 5, (although I doubt they would ever stop the adverts being recorded).
It`s a pity that the PDC system, (or something similar), cannot be used with digital, especially with so much football coming up, which often run to extra time.