Good Lord Liz we have got ospreys, nightjars, hen harriers, bittern, grasshopper warblers etc; etc; at Dyfi junction and its environs and you are concerned about 'moths'! (he, he!)
Actually you make a good point though there are an awful lot of extra lights on the extended platform at Dyfi junction which must surely affect the delicate balance of the Eco-system. Do you and Brian fancy coming up one summers evening with your moth trap? We could make it a birding group field outing for those creatures of the night! (no intended pun John Valentine!). Birdwise we should surely get nightjar and perhaps grasshopper warbler and sedge warblers which tend to sing at night like those other beautiful and famous nocturnal songsters, the nightingale, which I once heard on a spring evening on my honeymoon in Majorca with the aromatic scent of the 'maquis' wafting the air. Ahhh....halcyon days indeed! You never know guys you just might get some rare moths in your trap!