To the owner of the green car, registration S I5 SLOW: if you intend to go 10 miles an hour under the signed speed limit, fucking well do so in the fast lane, that is the right hand side lane.
The Highway Code is explicit:
“On a two-lane dual carriageway you should stay in the left-hand lane. Use the right-hand lane for overtaking or turning right. After overtaking, move back to the left-hand lane when it is safe to do so.”
“Once moving you should keep to the left, unless road signs or markings indicate otherwise. The exceptions are when you want to overtake, turn right or pass parked vehicles or pedestrians in the road.”
“Do not hold up a long queue of traffic … Check your mirrors frequently, and if necessary, pull in where it is safe and let traffic pass.”
Just because you have a “designer” licence plate indicating you are slow driver does not give you the right to block other road users in or prevent them from driving at, or even near the speed limit.