"I'm not the Boss!"
I'm not a Canon lawyer but as far as I understand it, the Cardinal Archbishop of Westminster is NOT the "leader of the Catholic Church in England and Wales". Many media outlets but particularly the BBC nearly always refer to him as such - see here, for example. Although he is the only Cardinal in England and Wales [un-retired cardinal - thank you too an anonymous pedant in the comments box], he is not the Primate (as the Cardinal Archbishop of Armagh is the Primate of all Ireland). Vincent Nichols is the Chairman of the Bishop's Conference but that is an elected post and he was elected to it long before he was made a cardinal. Westminster, as with other Archbishoprics, has several suffragan sees, which give the Archbishop certain limited duties and responsibilities under certain circumstances, usually when something has gone seriously amiss (Canon 435ff). Canon 436 §3 says: The metropolitan has no other power of governance in the suffragan dioceses. Even a Primate has no authority over the faithful outside his own diocese: (Can. 438) The titles of patriarch and primate entail no power of governance in the Latin Church apart from a prerogative of honour unless in some matters the contrary is clear from apostolic privilege or approved custom.
As I understand it, each bishop is the sole authority in his diocese with the next step up being the Pope as his only line manager (to use modern parlance). Again, as I understand it, we are not a "national church" in that way. I guess that the all pervading conception of the bishops' conference idea is responsible for this way of understanding things. Thus, when an individual bishop wants to speak out on what seems "out of step" with the rest of the bishops' conference, he might be reluctant to do so. Obviously, it makes sense for bishops to co-operate in individual countries so that there might be common practice. But this doesn't always follow - in the practice of the age of Confession, Confirmation and Holy Communion for example. Such differences don't seem to make us fall apart.
I do wonder that someone doesn't formally make the BBC aware of its mistake and ask that Aunty Beeb tries to get it right in the future. Perhaps some Monseigneurial mandarin in the Department of Administrative affairs at Eccleston Square could find time to do that. I know that this isn't the most important thing in the world but it does lead to a misconception being propagated. I've certainly heard of folk saying they will "write to the Cardinal" when they haven't had the answer they wanted from their bishop.