no it wasn't - a Mr Wallace was dismissed - as I said there were no mentions of the StePhensons - my guess they were appointed post 1877 - they may well have taught in another school before that - eg Minnie was bapt in Maughold - whereas if they were at Jurby surely would have been baptised in Jurby.
Most the info you want would be in manuscript form held at manx Museum - various minute books of the education committees or pre there formation the vestry books of the parishes.