Thank you all for your comments and suggestions.
David - this felllow must be the WW Marshall & Hannah I had heard of. I am interested in hearing if you can make out the name (or otherwise know) who the third child is in the family - various versions have offerred Joshua, John & James - but I wonder if you think if might be Jas.Wm.? Do you have links with that family? The painter you found doesn't quite fit with what we hade from his mother-in-laws' letters when he first arrived in NZ, so I doubt, though cannot of course yet exclude that as a possibility.
Trish - doh! I have so searched for his family for years, and have copies of BDM certificates for almost all my other ancestors including his wife Jane. But I have not done that for him, thanks for the prompt.
Will do, however I doubt it will offer anything much in this instance - our civil death certificates did not include names of parents until late 1875 & he died in 1873.
Diddy - many thanks for your kind offer. I did go through the parish christening films of about 12 parishes in the Leicester records office, but didn't really see much more than online searches. Having said that, I don't know his church - once married, he allowed his wife to attend CofE, but he was not much of a churchman himself.
Thank you all,
jo