Tim has some 1959 and 1959 Motor magazines on his bookshelf, so May 20th 1959 shows:
SWB Petrol £650 no purchase tax
SWB Diesel £740 " " "
LWB Petrol £730 " " "
LWB Diesel £820 " " "
LWB de luxe Petrol £750 " " "
LWB de luxe Diesel £840 " " "
SWB Station Wagon £740 plus Purchase Tax = £1049 9s 2d
LWB Station Wagon £860 plus Purchase Tax = £1219 9s 2d
Peter