These probably date back to before the 18th century
They are normally square, with a fringe and are usually of natural colours (black, white, cream). plain red shawls were worn in some parts of Wales (especially, it seems, in north Pembrokeshire see Fishguard invasion).
There are several surviving shawls which are claimed to have been worn when the French attempted to invade Britain near Fishguard in 1797. One is of a fine plain red wool, much moth eaten and repaired, said to have been worn by Jemima Nichols but its actual date is difficult to establish. (Pembrokeshire Museums 10.86.PM) Another is a paisley shawl which is certainly not the type described by the contemporary and subsequent accounts. (J S. Kinross, Fishguard Fiasco. Tenby, 1974).
References to traditional shawls
1774, St David’s
Mary Yorke noticed that a woman in St David’s Cathedral wore a square piece of flannel over her shoulders fastened before with a thorn. (Mary Yorke, Wrest Park papers (Lucas), Bedfordshire County Record Office, Transcriptions of the letters at Gloucester record Office, D2240/box 22; Jones, Anthea, Letters from the Bishop’s wife during the Episcopal visitations of the diocese of St David’s, 1774-1778, Carmarthenshire Antiquary, XXXVIII, (2002), 14-35.)