William was born in Perth prison to his mother Margaret Mustart.
In Glasgow, he became a student of the artist Thomas Fairbairn, a noted painter of West of Scotland locales.
By this point William was trading as an artist and upholster at 151 Sword Street in Glasgow's east end.
Marion's father, John Jackson, was a joiner, and Lockhart's business soon expanded to include picture restoration and furniture making.
He was diagnosed with bronchitic asthma, but shortly afterwards died of a pulmonary oedema on 3 January 1941.