Before the flotilla he posed with former co-star Windsor, who starred alongside McFadden in the soap for 16 years, in front of her namesake, the 40ft Dutch barge 'Barbara'. The photos can be seen in the recent souvenir Jubilee edition of Hello! magazine.
The 53-year-old actor then held a large RNLI flag aloft aboard the boat during the pageant, a celebration of the 60-year reign of the Queen, who is patron of the RNLI.
McFadden later said: "Being as keen a royalist as I am a sailor, I was pleased as punch when I found out I had been accepted to take part in the Diamond Jubilee Thames Pageant.
"It was a fantastic experience to be part of history, and also to have my own Windsor aboard!
"Flying the RNLI flag was my way of recognising the brave and courageous volunteer lifeboat crews, knowing the great life-saving work they do and the spirit they do it in whenever their pagers sound."