The London Gazette, and probably the Edinburgh equivalent should have his name in a list of awards, but not all MCs had a citation in the Gazettes.
A newspaper published near his home might have a report. The war diary of his battalion or equivalent might include a reference to the award with a mention of the incident leading to the award.
Some MCs appear to have been given in New Year or Birthday Honours, and will not have any citation.
A warning: the Gazettes' search systems are not the best to use.