As I live not far away, I took a walk down to the line this afternoon. The location of the slip is where the River Goyt is at its nearest to the line, maybe 20m away. About 5 years ago there was significant work on the line at this point, the work compound took over the nearby car park/playground at Hague Bar for several months (once finished NR restored the playground with good quality equipment, much to the delight of the local children, I'm sure!). The contractor Murphy has established a small compound on this car park, nothing happening today (Good Friday). The parallel road has often had similar problems, especially near Strines, where it tries to slide down into the Goyt - "single line working" or even closure is not unusual for motorists. There is recently laid ballast on the affected line, the shiny rails on the Marple side suggested that something had been along it very recently (overnight?) - was this an attempt to stabilise it?. The up line (still in use) also has its problems with a layer of large stones laid on the foot of the embankment next to the line by the road bridge at Hague Bar. This doesn't look like a quick job to fix!
As to the recent rainfall, we haven't had the deluges reported elsewhere but rarely more than two dry days at a time - but clearly the ground is full of moisture. The River Goyt is higher than normal, but it's been much worse than this in the past few years. The land slip has probably been building up medium term rather than a short term effect.