According to Lewis Lloyd in his booklet 'De Winton's of Caernarfon, 1854 - 1892' R.M.Preece, Banker and father of Sir William Preece, lived at Bron y Gaer in th 1840's until 1845 when he and the family left to live in London, twelve months after serving 2 years as Mayor of Caernarfon.It was in the 1850's sometime that another well known Caernarfon man, Owen Thomas of Tithebarn Street went to live to Bron y Gaer. He was a Foundry Owner and in 1854 went into partnership with Jeffreys Parry De Winton, the company then becoming known as Thomas & De Winton.In the 1861 census Owen Thomas, his second wife Sophia; unmarried daughters Catherine 21 and Ellen 19; his sons Owen 16, Hugh 14 and Edward 12; also his sons by Sophia, James Martin aged 6, Charles 5 and Frank 3; and two domestic servants Janet Evans, aged 28 of Caernarfon, Housemaid and Elizabeth Roberts, 23, cook of Llanrug.
You will see that there are gaps in the ownership of the house from when R.M. Preece left and Owen Thomas took up residence so it appears that you will have difficulty in tracing the names of the domestic servants you refer to.

T. Meirion Hughes

Many thanks for the information it has been of great help.
Regards Val John