Hobbits came in two versions:
Early red ones were 20 mph capable
Yellow ones were 30mph capable.
If I recall correctly, at the end of production, the red ones were also 30mph rated. But, if I am wrong, I am sure that someone will chime in with the correct info.
The nameplate on the headstock should show whether the bike is a
PA50I (20 mph version) or PA50II (30mph version)