Sandwiched the liner between two pieces of protective fleece.Yes, that's snow on the liner. Yes, those are Marigold washing-up gloves.
Emptied the contents of two water-butts into the pond while easing the liner into place.
Not too much excess to trim.The online pond-liner size calculators seem to yield very inflated figures. I recommend trailing a piece of string across the longest/deepest cross section and adding 0.5m, width and length.