Very nice. Probably a 1927 Special, or maybe even the 80-mph Sports. The cooking model, called the Standard, had the muffler across the frame in front of the engine right up until 1928.
Although it looks like no brakes are fitted, there are rim brakes front and rear with the brake rim fixed to the wheel rim, with flat shoes pressing on them. They were even coupled, so applying the foot brake applied front and rear brakes simultaneously. Famously Rudge introduced their 8" drum brakes for the 1928 season, which corresponded with their rise to the top of the racing tree. In 1930 Rudge were so dominant in racing that they filled 5 of the 6 podium places in the Junior and Senior Isle of Man TT races.
The original owner chose to decline the electric option, going instead for the ML magneto and carbide lights.
Cheers
Leon