"The Origin of English Surnames" by P H Reaney 1967 published by RKP (Routledge & Keegan Paul Ltd). .
"New names from France - following the Conquest, saint's names were less common, but gradually became more popular - Thomas from the Doomsday Book and Bible.
"Thomas, an Aramaic name 'twin' with petname Tom and diminutives in -in, -et, and -elin, eg:-
Thomas, Tomas, Thomazin, Thomasset, Thom(p)sett, Tom(p)sett, Thomasson, Thomerson, Thom(s), Tom, Tome(s), Tombs, Toomb(e)s, Thom(p)son, Tom(p)son, Tomsen, Thomline, Tomalin, Tomlin(s), Tomline, Tomblin, Tombling(s), Thomlinson, Tomlinson, Tombleson, and in North Lancs - Townson, Tolson, Toulson, Towlson, Tamlin, Tamlyn, Tamblin(g), Tamblyn, TAMPLIN(G), Tamplen,Tomkins,Tomkies, Tomkys, Tompkin(s) and Tom(p)kinson."
An alternative theory is that the name has Welsh origins associated with Owain Gwynedd, a Welsh king, who lived in the period 1137-1169. Madoc - one of Owain's (Owen's) sons - a prince of Wales - is reputed to have been an adventurous and knowledgeable sailor / explorer, who twice sailed across the Atlantic and discovered America in the year 1170, many years before Christopher Columbus. (Reference: Madoc and the Discovery of America by Richard Deacon - published by Frederick Muller in 1966)
The result of his voyages was the founding of a Welsh speaking, fair skinned tribe of American Indians. To commemorate this achievement, a plaque was erected in 1953 by the Virginia Cavalier Chapter of the Daughters of the American Revolution at Mobile Bay, Alabama, which reads " In memory of Prince Madoc, a Welsh explorer, who landed on the shores of Mobile Bay in 1170 and left behind, with the Indians, the Welsh language".
Madoc had a son Lynne, who had a son Thom, who took the name Thom ap Lynne Madoc. Eventually the name became Tamplynnech and finally Tamplin.
There are also references to the Knight Madoc in "Bullfinch's Mythology - The Age of Chivalry or Legends of King Arthur". The text speaks of Arthur meeting Madoc whilst camped at Caerleon - across the ford of the River Usk in Wales.
There is also a poem about Madoc written in 1805 by the English Poet Laureate - Robert Southey.