Hello Trish
Thank you so much for all the trouble you've taken. When I looked at the mc again I realised that John's age could be read as 35 and if this was correct then the info in the 1881 Census for John and Ann at Ruthven Lane is correct. In the 1891 Census re their children, Peter, 12, would be my grandfather, Christina has her maternal grandmother's Christian name, Margaret has her paternal grandmother's name. Ann Lawson (Watt) was born in Udny, Aberdeenshire and the marriage date is 1877 not 1888. I will try later on tonight to find a birth certificate for John and see if there is further info re his parents.
Thank you once again