The patent for Munstead Wood seems to want to point out that this rose has few prickles (as a comparator to MW). Looking at the photos, and never owning Port Sunlight, it seems this implication is true. Many photos are void of any prickled stems, and a few photos show some prickles. A good trait for large roses and winter pruning time.

the fragrance of "port sunlight" of austin is strong.
see：
http://www.davidaustinroses.co.uk/port-sunlight