"A hamlet, in that part of the parish of Gresford which is in the hundred of Bromfield, county of Denbigh; 5 miles (N by W) from Wrexham; containing 539 inhabitants. It is situated near the left bank of the river Alyn, and on the border of Flintshire. ..... Offa's Dyke passes between the township and the river." [A Topographical Dictionary of Wales, 1833 & 1849, Samuel Lewis]
Llay became a parish of the Church in Wales on 13 December 1944. It was formed from the township of Llay, and parts of the townships of Burton, Gresford, and Marford & Hoseley, which, until then, been in the parish of Gresford.
Llay village trail with brief history & photographs of Llay Main Colliery / produced by the Clwyd County Planning and Estates Department in association with the Llay Women's Institute. Clwyd County Council, 
Nicholson, Arthur D. Explosion at the Llay Main Colliery, Wrexham, Denbighshire London : HMSO , 1925
Tilston, Jeremy. The Tilston family of Llay smithy (1661-1991). Part 1, 1661-1704 Hel achau, 36 (1992), p. 2-5.
Tilston, Jeremy. The Tilston family of Llay smithy (1661-1991). Part 2, 1704-1842 Hel achau, No. 37 (1992), p. 13-17
Tilston, Jeremy. The Tilston family of Llay smithy (1661-1991). Part 3, 1840-1991 Hel achau, No. 39 (1993), p. 8-10
Ordnance Survey reference SJ 333557.
The first services at Llay were held in the "Mission Hut" on 9 January 1916. The foundation stone of the new church, which is dedicated to St. Martin, was laid on Sunday, 11 November 1923, and the church was consecrated on Saturday, 21 February 1925.
The Clwyd FHS website has a photograph of the church.
"Welsh Church Commission - County of Denbigh - The Statistics of the Nonconformist Churches for 1905" did not list any nonconformist places of worship in the Civil parish of Llay.
The following Parish Registers have been deposited at the Denbighshire Record Office, Ruthin.
They may be viewed on microfilm at the Denbighshire and Flintshire Record Offices, at the A.N. Palmer Library, Wrexham, and at the National Library of Wales, Aberystwyth.
These microfilms are not available elsewhere.
Baptisms which took place at the Mission Church before 21 February 1925 have been entered into the baptism registers for Gresford.
1925 - 1961
1925 - 1971
There are no Bishop's Transcripts for St. Martin's, Llay.
There are no official I.G.I. entries for St. Martin's, Llay.