This cache is on the doorstep of Newtown Textile Museuem. The buildings along this road were mostly built in 1830, and provided accomodation and factory space. The bottom 2 floors of the building were back to back cottages. On the top 2 floors were several handlooms, that would have been used to weave the famous welsh flannel. The looms would have been loacted one per window, so a quick bit of counting reveals the number of weavers employed in this building. They were built at the heyday of the textile trade in Newtown, but most of the cloth was still woven by hand, rather than the giant cotton mills in the Lancashire area, or the woolen mills of Yorkshire.
Take a look at the buildings around Newtown, any that have large numbers of big windows on the upper floors would have housed a small scale factory. Later on in the century bigger mills were built, but the whole history of the trade in the area was one of boom and bust, and many of these bigger factories "burnt down", allowing the owners to claim insurance payouts, and were never re-opened.
There's roadside parking with in spitting distance of the cache, or the streets behind the museum usually have space if you think you'll need more time to explore the town.