The actor who played Morant was none other than Edward Woodward - probably best known in the US for playing a middle-aged vigilante type, but a darned good actor and not a bad singer too. In the UK he's probably best remembered for Callan (Shite, showing my age here) and for playing the God-fearing copper in the Wicker Man.
He did a number of recordings of 19th century soldiers' songs - including Soldiers of the Queen - for the National Army Museum in Chelsea a few years back, but I don't know if they were ever issued for sale.