I'm going to give possible candidates for William Henry's parents. If you look at John Lyall & Catherine Robina Ellison's marriage record one of the witnesses is Catherine Ann(e) Sharpe. The marriage took place at Maughold on 29th July 1888. On 1st May 1888 Catherine Ann(e) Sharpe, a domestic servant, had a son called William Henry at 21 Church Street in Ramsey. Birth registered 31 May 1888. He was baptised at Ramsey on 19 Sep 1888. At an ecclesiastical court held at Douglas on 28 June 1888 the father was affiliated to the child and named as William Henry Christian of the ship Juno of Ramsey. I think these might be William Henry Lyall's birth parents before he was adopted by the Lyalls.