Thank you for your very informative message about the original St Ann's Church.
I have some evidence that it was built in about 1812 St Ann's Centenary Souvenir; Gwynedd Family History Soc. Memorial Inscriptions No M396. The 1st incumbent was Morris Hughes (1812-1860). However, I have the same doubts as you when you consider that it was named after the wife of Richard Pennant, Anne Susannah Warburton (1745-1814) and Richard had died in 1808 so it's a bit late to build it in 1812 when George Hay Dawkins had inherited the estate by then. Do you have concrete evidence? I also think the vicarage was the large house called Bryn Llys - just below Lon Goch and it was inhabited in the 1881 census by David Pritchard - a quarry agent, with his wife, family and 3 servants.
Thank you too for the information about your grandfather. The M396 lists the following organists/choirmasters but has no dates: Evan W Thomas Ty'n Clwt uchaf and later of Bangor, John Hughes - son of the above - (Eos Ceraint), Tai Duon, Coed y parc, Johnny Hughes, Cherry Cottage, Bryn Eglwys, Thomas Jones, Penygroes, Tregarth, Edmund Vale, Bethesda and William baden Powell Evans, Coed y parc in 1965.
Any additional information of the area would be most welcome.
Diolch.