Rivendell Sam Hillborne, Brompton S/M3L (modified)
I don't own this bike but I wouldn't hold out much hope with that tire fitting. The stock bike comes with 25c tires and you want to put on something that is considerably larger. As I looked at photos of the bike it looks pretty tight as it is.
Certainly someone with more expertise than me can chime in.
That Marathon Plus won't fit the stock wheels of a Chameleon (ERTO 520) but would fit the stock wheels of a Joey (ERTO 507) .. there are a handful of tires that I have run on my Chameleon ... right now I'm running the Specialized Mondo 25x520 .. which is a slick, more compliant than the Panaracers, and still an easy rolling tire..