These days you may access maps on your phone, using the OS app or another dedicated mapping app, such as MemoryMap. These are great for pinpointing exactly where you are at any time, and the zooming in facility on the screen saves getting out the glasses!
However, if you want the relevant OS paper map for Trefriw and the area covered in our walks, the one you need is Explorer (OL) 17 (1:25,000 scale).
(Statistically you’re likely to have a copy already – this is the Ordnance Survey’s top-selling map!)
On one side is the Conwy Valley, with Trefriw sitting fairly centrally in it; all our walks lie on this side of the map. The other side is dominated by the Snowdon massif.
If the 1:50,000 is what you want, we’re on the very edge of Landranger 115.