Kirk Yetholm isn’t a German sitcom character, but a hidden classic Scottish riding location a stone’s throw north of the English border. Words & Photography PETE SCULLION Think bikes and the Scottish Borders and Kirk Yetholm probably won’t even be in the top ten places to turn a wheel on dirt, but there’s much more on offer than plantation tree slaloming – although that is an option if you’re willing to work for it. The…