Opened in 1879 and built to the first GWR standard design, it was set up to control the GWR's mainline onwards to Penzance, together with the junction for the branch to Newquay.[1] Located at the southern end of Platform 2, when first built it was less than half its current length, only containing 26 levers. In 1913, the frame was replaced, and a new frame of 57 levers was added.[1] A panel has since been added to control the section through to St Austell and Burngullow as far west as the now closed Probus and Ladock railway station. Signals controlled from Par carry the identification code 'PR'.
In January 2024, it was announced that a number of signal boxes in Cornwall, including Par, would be closed in Spring 2024, with signalling moved to Exeter.[4] The signal box was decommissioned on the 4th March 2024.[5]