Complex sentence: It is one of the original nine British public schools, the so-called'Clarendon Schools' investigated by the Clarendon Commission set up in 1861 however it was argued successfully that the school should be omitted from the Public Schools Act 1868.
Split into simpler sentences: It is one of the original nine British'Clarendon Schools' public schools, investigated by the 1861 Clarendon Commission. However, The School successfully argued that the school should be omitted from the Public Schools Act 1868.