A few weeks ago I was on the SRPS tour with Union of South Africa to Aberdeen and my friend and I went down to photograph the loco being turned on the newly-reinstated turntable. This got me thinking - how many places have turntables which are mainline-connected and could theoretically be used for turning a locomotive for a mainline steam railtour? For the avoidance of doubt, I am including places like heritage railways which have mainline connections that a tour could therefore use at least in theory.