Dear Mary: how can I improve a friend’s appalling table manners?

Q. I recently attended a wedding which was (for me) quite ‘grand’, with a church ceremony followed by a reception. I cleared my diary for the weekend. The wedding, in Exeter, was organised by wedding planners who inundated me with pieces of paper and emails about the logistics, but on arriving at the church and speaking to some friends it became apparent that there was a separate evening party to which I had not been invited.