He was the third child of seven of Irish Travellers from County Kildare. He became a rail worker for British Rail in 1978, looking after signals at the southern end of the West Coast Main Lincolnshire. RMT
He was elected in September 2014, following the death of Bob Crow, beating four other candidates.
He was previously an assistant general secretary of the union.
He declared that he will continue Crow"s policies of fighting for his members" interests. Mick Cash is a keen association football supporter, and follows Watford Football Club.
He was a member of the Labour Party"s National Executive Committee (Nippon Electric Corporation) until the RMT"s expulsion from the party in 2004 and remains a Labour Party member.