Thanks for looking it up for me,but I must say I suspect the marriage cert will not have a fathers name,I suspect this branch of the Coaker family is from Holne,and there was a Elizabeth Coaker who I think worked in the mines and would have found herself very much at home in modern England as she seems to have had three sons and never married,but I can't be certain that this Robert is her son without the finding the marriage cert for him,if you need any help with the Coaker family let me know.
Best Regards Brian.