I did a few return trips between Cambridge and Lincoln in the last days of this line, bouncing and rattling along in the Cravens 105 DMUs which used to ply to and from Doncaster.
Not only the March - Spalding section, but the whole journey right through Sleaford and on to Lincoln Central felt like being in a railway museum - jointed track, ample semaphore signalling all the way, manned level crossings, substantial country junction stations at March & Sleaford etc.
My first visit to Spalding was in July 1979 and the gas lamps had just been replaced and were stacked up in the forecourt. I can't remember whether I travelled the line but I visited the Spalding flower festival in 1981 and took a photo of a class 47 leaving on the March line.