A service was held outside the war memorial in Bridge Street to mark the occasion.
Flags were raised and a wreath laid by branch chairman Graham Casey.
Long service presentations were also held for Margaret and Jerry Wilson who are retiring after 25 years of standard bearing.
Branch secretary Tony Francis said: “I would like to thank all who attended in support, including the Peterborough Sea Cadets from TS Guildenburgh who turned out to help build the bridge between generations - they did their unit very proud.
“On a whole it was a memorable small service to mark the occasion, especially during these trying times, and everyone did me proud and I am thankful for their attendance and support.”
Long service presentations were also held for Margaret and Jerry Wilson who are retiring after 25 years of standard bearing.
5. 100 year celebration for the Peterborough Royal British Legion
Jason Hobson playing the Last Post EMN-210627-170346009 Photo: Midlands
6. 100 year celebration for the Peterborough Royal British Legion
The service Photo: Midlands
7. 100 year celebration for the Peterborough Royal British Legion
The service at the war memorial Photo: Midlands
8. 100 year celebration for the Peterborough Royal British Legion
The service at the war memorial Photo: Midlands