Complex sentence: The gang had been responsible for a series of bombings and killeds in London included the assasination of Conservative political activist and "Guinness Book of Records" co-founder Ross McWhirter after he offered a reward for their capture.
Split into simpler sentences: The gang had been responsible for a series of bombings and killings in England. This included the assasination of Conservative political activist and "Guinness Book of Records" co-founder Ross McWhirter after he offered a reward for their capture.