We went down and sat in the car by the tracks last night, to get a general feeling for the noise. Don't get me wrong, the house is further away than the road but you'd still hear it quite noticeably when in the garden. I'm interested on the viewing to hear what it's like from within the house. There was some passenger trains that were pretty quiet, lasting for about 5-6 seconds at a time - not a problem. There were though, freight trains lasting 10 - 15 seconds and rattling and really noisy. I tried to downplay it to my partner because she was massively unimpressed but to be honest she was right - unless they've done a good soundproofing job in the barn conversion (which I can't imagine they will have done, they'll have done it as cheaply as possible) then there's no way you won't hear it.
Typically, on a normal day, having looked it up, about 400 trains go past, so it's near constant. I think it may end up being a deal breaker, we'll have to see. There will be 8 trains going past in the 30 minute slot we have on Saturday. We'll have to see - but it's clear now that the tracks are the obvious reason as to why this property is £50k - £70k cheaper than if it was 1/2 a mile up the road.