A state and national representative forward, he played five Test matches for Australia, one as captain.
Hardcastle was born in Buenos Aires, Argentina and attended The Scots College in Sydney.
He played in three Tests and seven tour matches proving his capability as a durable tight forward, formidable in the ruck.
Though a tall man Hardcastle was not a proficient jumper and often adopted spoiling tactics to prevent opposition locks getting above him in the line-out.
This affected his ability to communicate quickly on-field but also led to an amusing incident on the 1947-48 tour when Hardcastle was nominated after the Swansea match to give the traditional visitor's response to the after-dinner speech.