It is because one of the platforms at Victoria is shorter than the
others. I think it is platform 7 from memory. It takes the system a
bit longer to open the doors because it has to confirm that it is at
the right platform.

The system also has a problem at smaller two platform stations if one
platform is shorter than the other. There was a case where the london
bound platform could take 12 coaches but the country one only 8. As
the GPS was not sensitive enough to tell which platform the train was
at it would only open 8 coaches in both directions.