Origin of "-le-" article in English placenames such as Newton-le-Willows, Bolton-le-Sands, Houghton-le-Spring?

The main theory for Houghton-le-Spring is that "le" means "in the"

as evidenced by The Regester Booke — belonginge to the Paryshe of Houghton in the springe from the yere of our lorde god 1563 vnto this present yere 1598 conteininge, Weddinges, Christninges and Burialles

Prior to being "Houghton le Spring" it was Houghton in le Spring

http://www.houghtonlespring.org.uk/main.htm

Apparently, some date back to the 13th century, but others are much later. It will depend on which one you're talking about:

An interesting example of this is the class of names of the pattern of Chester-le-Street in County Durham. There are at least ten examples of this formation in the one county. For a thousand years from the eighth century Chester was simply Cestre, Cestria; in 1406 the Latin addition in Strata appears, 'on the Roman road', Frenchified as Chestre in le Strete in 1411, and simplified to Chester-le-Street from 1607. The other nine are [...] Houghton le Spring (Houghton in le Spryng 1410-1556) [...]

Elsewhere there are earlier examples: in North Yorkshire, Thornton le Street is in via 1208, in strata 1268, Thornton le Moor in mora 1208, Newton le Willows in le Wilughes 1300.

But others are only fifteenth or sixteenth century - Thornton le Beans, in le Beyns, in Fabis 1534, Barton le Willows, in the Willos 1574, Norton le Clay, in the Clay 1536...

_{English place-names in the sixteenth century: the search for identity}