The shootings of Miners at Tonypandy story seems to have come from a documentary novel written by a trades union organiser.
The piece below comes from Wikepedia at
Purported eyewitness accounts of alleged shootings persisted and were relayed by word of mouth. There are no records of any shots being fired by troops. The only recorded death was Samuel Rhys. In the autobiographical 'documentary novel' Cwmardy, contemporary communist trade union organiser Lewis Jones presents a stylistically romantic, but closely detailed, account of the riots and their agonising domestic and social consequences. In the chapter Soldiers are sent to the Valley, he narrates a fictional incident, in which eleven strikers are killed by two volleys of rifle fire in the town square, after which the miners adopt a grimly retaliatory stance. In this account, the end of the strike is hastened by organised terror directed at mine managers, leading to introduction of a minimum-wage act by the government – hailed as a victory by the strikers.
A more official version states that "The strike finally ended in August 1911, with the workers forced to accept the 2s 3d per ton negotiated by William Abraham MP prior to the strike ... the workers actually returning to work on the first Monday in September", ten months after the strike began and twelve months after the lock-out which started the confrontation.