Thank you ScotMum...some great pointers. I have found the shipping record for James snr, Jeanie and Jessie aboard SS Balranald departing for Australia 23 Dec 1926...confirmation of address in Wishaw as 37 Bute Cres, Belhaven Rd.
Haven't found James jnr but will keep looking in 1921. I still need to find Catherine, William and Agnes. I did assume they would all come out together but I was way out on that one! I've also searched UK incoming for William but I'm not sure he made it back to his homeland. I have to keep an open mind on that.