Logically, yes. But like everything it'll take another 10 years before they change it and by that time 7-11 might have changed too. I'd just say, 1st year at college.
The school system didn't always run from Year 1 to 13. In the older system, when you went to secondary school you went into the First Form & did your O Levels (now GCSEs) in Fifth Form. If you stayed on to do A Levels you went into the Sixth Form, which was divided into Lower & Upper Sixth Form to cover the two years.
The system was only changed to run from Year 1 to 13 in the 1990s.