When E4 follows a C4 programme with the next episode, they often overlap by 5 minutes. Desperate Housewives used to do that. They often seem to pad out one of the programmes with an overdose of adverts and include that in the rounded-up scheduled time. It is very frustrating.
It seems it is again all down to the BBC being unwilling to use real time - but five minute blocks.
Dr Who started about one minute early (1859 instead of advertised 1900)
Dr Who finishes at 1942 - next programme advertised at 1945 start.
Dr Who Confidential started at 1943 - so advertised time was changed from 1945 to 1940.