Jag driver in the wrong both times and bang out of order IMO.
I know there is something in the statutes going back to the days of horses and carts which says you must keep to the left to allow vehicles to overtake you but that is archaic and probably wouldn’t be relevant in this situation. I think that is what the Jag driver must have been referring to and here is what it says FYFI:
Section 78 Higways Act 1835:
Or if the driver of any waggon, cart, or other carriage whatsoever or of any horses mules or other beast of draught or burden meeting any other waggon, cart, or other carriage, or horses, mules, or other beasts of burden, shall not keep his waggon, cart, or carriage, or horses, mules, or other beasts of burden on the left or near side of the road;
Or if any person shall in any manner wilfully prevent any other person from passing him, or any waggon, cart, or other carriage, or horses, mules, or other beasts of burden, under his care, upon such highway, or by negligence or misbehaviour prevent, hinder, or interrupt the free passage of any person, waggon, cart, or other carriage or horses, mules, or other beasts of burden, on any highway, or shall not keep his waggon, cart, or other carriage, or horses, mules, or other beasts of burden, on the left or near side of the road, for the purpose of allowing such passage
The guy may have a point but it’s not a very good one. He should have been paying more attention and being more careful.
That same section also says:
Section 78 Higways Act 1835:
…if the driver of any carriage whatsoever on any part of any highway shall by negligence or wilful misbehaviour cause any hurt or damage to any person, horse, cattle, or goods conveyed in any carriage passing or being upon such highway…
So the chances are that He could be guilty of breaking the very law that he was accusing the rider of breaking.
BTW it all ends with " …shall in addition to any civil action to which he may make himself liable, for every such offence forfeit any sum not exceeding level 1 on the standard scale." (words in italics substituted by criminal justice acts of 1967 and 1982 but the rest of what is quoted is unrepealed)