I think there is some confusion generated by the bbc article. As Lavaterguy says, your post is the one commonly found in Britain; it has the yellow collar. The “new” snake Natrix helvetica, now a distinct species, is called the barred snake. Not because of the yellow collar, ( which it doesn’t have) but because of darker body markings.
So yes your post is the barred grass snake, Natrix natrix.
I found this site helpful in writing this comment. The barred grass snake info appears to have been added at the end, in 2017.