I have the raster tiles for the OSi DISCOVERY (1:50 000) maps and need to view them through the Google Maps API slippymap as a custom map type (e.g. Map/Sat/Hybrid/OSi).
There are 236 Tiff tiles altogether covering Ireland. Each of these tiles covers an area of 20k x 20k.
We can break them down into 256*256px tiles for Google (googletilecutter.sh) but are unable to set the slippymap to the right projection (Irish Transverse Mercator).
The same problem will exist for the UK OS maps so a system for ourselves to do this in the future would be best.