Complex sentence: In 1279, the country's numerous mints were unified under a single system whereby control was centralised to a new mint within the Tower of London, mints outside of London were reduced with only a few local and episcopals continuing to operate.
Split into simpler sentences: In 1279, the country's numerous mints were unified under a single system wereby control was centeralised to London Mint. Mints outside of London were reduced with only a few local and episcopal continuing to operate.