Hello Basil, to rule out the first John, you need to check the Parish Register of burials,

Jn, Jon, Jno, are all forms of John,

Have you looked for Memorial Inscriptions for, John and Catherine Bridson, sometimes they have the names of Children who have died in infancy,

This message board is very helpful with everything, including Memorial Inscriptions,

even a look up for a Memorial Inscription for, William and Margery Bridson could be helpful, they may have plot numbers near each other,

glad to have been of help, Averil