Two were used at MO laterly, the Clayton (yellow one now in mill) was used underground (Floor 😎. I too have heard stories of it being run up and down at various times (alledgedly). They also used a BEV (NOT BVE!) in the mills this was moved to Llechwedd at some time and now resides at far end of the Quarry Tours "Miner's Tramway" apparantly kept there as a maintenance/emergency loco. Although when I was shown it it looked as if it needed rescuing itself!