Here is a PDF info-sheet, plus photos, about the very handy magnetic strip secondary glazing which I have on my windows.
I also in 2015 made a short (9-minute) video,
in which I and a colleague tell you about its advantages and show you how it's installed.
As at February 2021 it's had well over 100,000 hits, and some useful comments; please do watch it!
Magnetic strip secondary glazing is inexpensive and easy to do; it's unobtrusive (good for conservation zones and listed buildings) and very long-lasting; it does the same job as expensive secondary glazing systems. I achieved brief fame in 2014 in a piece in the Sunday Telegraph, talking about this very useful energy-saving measure.
Click on photo for larger image