CAP 493 previously limited the Aerodrome Controller role to ‘assisting’ in preventing collision with regard to the manoeuvring area and the apron, and specified this as a specific responsibility of Aerodrome Control, whereas ICAO PANS-ATM states that prevention of collisions is an objective rather than being a direct controller responsibility. Therefore, the change in the CAP 493 MATS Part 1 wording from a direct responsibility of Aerodrome Control to an objective is considered to balance the change regarding from ‘assist in preventing’ to ‘prevent’.
IMHO this means that, from tomorrow, EGLL ATCO's can no longer issue a clearance into an area where they know there is a risk of wingtip hits due to restricted clearance. Putting info on the ATIS as mitigation doesn't seem to cover it any longer.