Quentin Blake, one of Britain's best loved illustrators, won the 2011 Prince Philip Designers Prize.
This is the final year that HRH The Duke of Edinburgh will deliver the Prize. Having headed up the judging panel and presented the Prize since its inception in 1959, he will be stepping down from the Prize as he reduces his work-load and royal responsibilities in his 90th year.
To mark the occasion, Quentin Blake illustrated this special certificate of thanks.
Special commendations were also awarded to Saeed Zahedi and David Chipperfield. Find out more about the winners and who else made the 2011 shortlist