There are around 1,300 places in Cornwall whose names contain the element tre, meaning a farmstead, hamlet or more generally a settlement. It is no surprise therefore, to find many surnames derived from those placenames. In 1861 there were around 125 separate Tre- surnames, amounting to 2.9% of the Cornish population. Over the centuries no doubt, some Tre- surnames have become extinct, others fallen together with more numerous similar names, while a proportion of places beginning with the element tre did not give rise to a surname.
Sometimes one place could give rise to more than one surname. This is so in the case of Trewern, the final surname on my list of rarer Cornish tre- names. There is a place of this name in Cornwall, a farm at Madron, near present-day Penzance. This was originally Treyouran, or Uren’s farm, Uren or Urien being a common Brittonic Celtic first name. It was still a three-syllable name in the early sixteenth century when a Thomas Treowran was living in the neighbouring parish of Sancreed.
Over time, the three-syllable Treuren became the two-syllable name Truran and moved eastwards (see my The Surnames of Cornwall and the map here). However, some Treurens became, like the placename, Trewern, a Gabriel Trewern being baptised at Sancreed in 1634. Unlike Truran, five of the six Trewern families were still living in West Penwith in 1861, with one to the east at Stithians.
This westerly orientation of the name Trewern reflects the more general geography of Tre- surnames. All those areas with a higher than average proportion of Tre-surnames in 1861 were found west of Bodmin. This repeats the earlier pattern found in 1641. Then, a very similar 2.7% of adult men bore Tre- surnames. If anything, industrialisation and population growth in the west had reinforced this earlier pattern. The migration of miners to the Liskeard and Callington districts in the early 1800s did not fundamentally change the pattern.
It remains to be explained, given that Tre- placenames were scattered fairly evenly across Cornwall, why the surnames derived from them more likely to be found in west than east Cornwall. This must be related to the timing of surname formation and the cultural differences between English-speaking and Cornish-speaking communities. In the latter, there was a greater tendency to retain or coin surnames based on places. But was this just a result of the different, later timing of surname formation in the west, or something more basic?