IGI lists some of the children, including one born Oct.1867 in Glasgow wich may be reason the year of the marriage was put down as 1866. However, it is a submitted record and would need to be checked against the actual birth certificate to make sure.
There's also an Elizabeth born 1867 in Glasgow listed in IGI and one born 1877 in Pedigree Resource File who died in Scotland but her birthplace is listed as Co. Tyrone. Submitter's details listed.
See www.familysearch.org and do a search on advanced search page wit names of parents only.
I know for definate that there was an Elizabeth born in 1877 as she was my gt grandmother. I have a copy of her birth certificate. I suspect the 1867 one is wrong. I have copy birth certificates of all the siblings (11 in all) as well as the one for Beatrice, a grand daughter. Thanks for the advice aghadowey.
Regards
Laurence