Other navies needed time to digest the concentration of new equipment in one ship, while Fisher pressed ahead from a position of unusual security. Britain already possessed the only dreadnought and an enormous battle fleet, and it continued building familiar pre-dreadnoughts as well. Dreadnought therefore did not have to rescue the country from an immediate fleet crisis. That cushion let the Royal Navy use her as a viable test bed without depending on the prototype for national survival.
Chapter · 4:52-7:31
Why Britain could treat HMS Dreadnought as an experiment
Britain's large pre-dreadnought reserve gave it room to treat Dreadnought as a technological experiment while national survival rested on the existing battle fleet.