He was not that much more violent than his opponents until the Night of the Long Knives and the Enabling Act.
Even so, he had his own political ' stormtroopers', a bunch of people who fought for him, and him alone.

The existence of a band of folks in Britain , who have got batons and riot shields, working under the direction of local leaders is not likely to lead to a beer hall putsch.

A private Army, working for one person the way the Met Police worked for Thatcher is a different ball game, though. Abu hamza had one in Finsbury Park. But a written constitution should make a take over very hard to achieve, and if they did , they only have broom handles.