As promised here is an update. Lexus have declined to amend their stance and to be honest I am extremely disappointed with their customer service in this instance.
However Lexus Bolton have been superb. They amended the deal, gave discount, gave more money for my trade in and all in made the deal attractive. As a result I take delivery of my vehicle on Monday.
To sum it up, very poor show Lexus, excellent service from Lexus Bolton.