According to the fountain of knowledge known as Wikipedia, 5 months on a short service commission with the Black Watch.
Did he do OTC before this? 5 months does not seem very long to get trained and do the job.
Was Rory "Thunderbirds Parker" Stewart kicked out after five months?
The Short Service Commission (SSC) - the SSC is the normal first commission for those who become an officer in the Army. It is a commission for those who do not wish to commit to a long career but would like to benefit from the high quality training and exceptional experience available to young officers. The SSC is also a first step to a mid-length or full career in the Army. SSCs are awarded for a minimum of three years (six years for the Army Air Corps on account of the length of pilot training) but can be extended to eight.