Complex sentence: Pat O'Malley and Simon Wells are known as the two original founders of the Black Eagle Society, Simon after only a short time left the group leaving Pat in sole charge of the organisation which still host's events to this day.
Split into simpler sentences: Pat O'Malley and Simon Wells are known as the two original founders of the Black Eagle Society. Simon, after only a short time, left the group leaving Pat in sole charge of the organization which still hosts events to this day.