Demo map showing TIPLOC locations is at https://howff.github.io/tiplocmap/
The repo needs a branch called gh-pages and then it gets deployed via https://github.com/howff/tiplocmap/deployments/github-pages
I've added an OpenRailwayMap but not sure I integrated it correctly. Other map providers are shown here: https://leaflet-extras.github.io/leaflet-providers/preview/
TIPLOC data is from https://github.com/oweno-tfwm/YA_Tiploc_List
OpenRailwayMap is from https://www.openrailwaymap.org/
Demo leaflet from CSV came from https://handsondataviz.org/leaflet-maps-with-csv.html and https://github.com/HandsOnDataViz/leaflet-map-csv
Leaflet mapping is from Leaflet documentation.