Complex sentence: Its mosaics are known in Ireland, England, France and one in the U.S. Bizarrely for a Manchester based firm, most of their known work is in Ireland, so much remains to be learnt about their work in Britain.
Split into simpler sentences: Its mosaics are known in Ireland, England, France and one in the United States. Bizarrely, for a Manchester-based firm, most of their known work is in Ireland, so much remains to be learnt about their work in Britain.