That will be the GMC rubbish train going back empty. Us here in Lincolnshire are getting all Greater Manchester Area,s rubbish dumped on our side of the country in the old ironstone mines at Roxby Gullet. The originally provide the ironstone to the steelworks until it became uneconomical and was re[placed by imported ore, so the holes was left behind and our council have been tipping waste in them for a good few years. These trains having been running quite a few years now and I think there are 2 trains a day, 5 days a week. they run to Roxby down the old North Lindsey light railway.