Here's a Falcon (or so I believe) that was originally blue. Fork crown is different from yours (square-edged), and it has no serial, unless filled with repaint. It had a zerk fitting on the left side of the BB casting, and a cottered crank, different from yours. TDC (Cross) bottom bracket. The frame + fork weigh 3.6 kg bare, by far my heaviest one. Seat tube is seamed tubing, so probably not Reynolds 531, but it takes a 26.6 mm seatpost. It's my commuter. All the components seen here are replacements, except for the headset, which, as yours appears to be, is a Stronglight P3, or a simulacrum thereof (no "Stronglight" engraved on it).



Some more photos here.