I wonder if anyone has some good links as to who were the construction company/ies on the Lake Vrnwy Dam, Hotel, Church and new village.

I can find a lot as to the how and why but not the who, much of the information is just repeated from one reference to the next.

Here's hoping. Cheers.

Try this link http://en.wikipedia.org/wiki/Lake_Vyrnwy

Thank you Capt but I have trawled through a lot of google and am now trying to find out where all the written stuff is archived. I have put feelers out to possible locations and if I find anything interesting I will place it here.

Moonstar, surely Powys County Council could help. Archives Department, maybe?

Awaiting reply from National Library of Wales at Aberystwyth but sometimes these things take a while.

Found this.
The new church of St Wddyn was built by the Liverpool Corporation under the terms of the 1880 Liverpool Corporation Waterworks Act. Building began in 1887 and the church was consecrated in 1888, a week after the old church of St John’s had been flooded by the swelling waters of the new Lake Vyrnwy.
The new church is built in a free Arts and Crafts interpretation of Early English style, to the design of the architect F W Holme. It consists of a nave (the main body of the church), chancel (the east end of the building) with transepts and a pentagonal apse, and is built in the same blue grey stone as the dam and other village buildings constructed by the Liverpool Corporation.
http://www.living-stones.info/downloads/guides/14_Wyddns_Church_web.pdf

I realise this is quite an old thread, but to answer the OP the site here is a useful and interesting resource and the specific article on Vyrnwy is the first of many about the scheme.
https://www.gracesguide.co.uk/The_Engineer_1887/01/14