A second-half Josh Coley strike saw Buckingham Town exit the F.A.Vase at Baldock Town despite a resolute display.
The Robins lined up with skipper Sam Bearman returning to the heart of the defence in place of Enoch Sare in the only change that beat Thrapston Town in midweek.
Coley’s 65th minute strike was the difference between the two sides as they go through.
Next up for the Robins is a trip to Mursley United in the Berks & Bucks Senior Trophy, first round this Saturday.
Ryan Thrussell, Sam Tamakloe, Jelani Blair, Steve Gavrovski, Sam Bearman, Junior Muya, Brandon Bander, Jamie Nicholls (Capt), Danny Simpson, Kelvin Osei-Addo, Orlando Joao.
Subs: Daniel Silver, Enoch Sare, Murdy Maki, Fuad Ahmed.