It is great to hear there is a connection - we have recently sorted through some family photos and think my grandfather James Vannan Johsnton must have been corresponding with your family as we have photos and clipings of James Vannan Jnr from 1944 which appear to have been sent by James Vannan Snr. (my grandfather was Isabella Jane Vannan son)
Please email at nicola@johnston7776.freeserve.co.uk I would love to share more with you.
Ps Helen Vannan died in infancy - the McEwan information comes from the family tree I was given by one of Isabella's other sons. Look forward to hearing from you