There are fiche with a few irregular marriages for the late 18th century in Coldstream Bridge available - just a few of the many marriages performed there. These could be an option to check as Coldstream was the closest 'major' centre of irregular marriages to Kirknewton parish. Many got married at the time of big hiring fairs or other fairs - alcohol was apparently not an unknown accompaniment to irregular marriages. However, depending on where they lived in the parish, your couple may have just walked in complete sobriety to wherever the nearest 'celebrant' was operating over the adjacent Border at the time.
I have the fiche for Coldstream but no chance of getting to a fiche reader this side of Christmas
Another option is to order these through the LDS family history centres - see
www.familysearch.org for the address of the one nearest you. They will explain how you order and view films - the same entries on the fiche are also available on film and you might find other family members.
The other thing that might be worthwhile is to order films for the burials for Kirknewton & nearby parishes such as Cornhill and Ford. In that part of the world the only place you could be buried was in a C of E churchyard, whatever your denomination. By all means also see what is available for the nearby Scottish parishes such as Kirk Yetholm & Coldstream, however Scottish burial/death records are limited prior to civil registration and in quite a few places were either not kept or did not survive.
What were the occupations of Peter Hume and your other family members? Shepherds, hinds and agricultural labourers were very mobile and it is common to find families in the census with children born both sides of the Border, reflecting the families' movements.
You might find this site of interest
http://communities.northumberland.gov.uk/ - Kirknewton has its own section.
Matilda
