But now I think I may have joined the ranks of the true pioneers of Minor restoration

The liners were basically sound, just a bit distorted, but the flock surfaces were very soiled and stained. I tried cleaning with various products, and although they improved they didn't come up to the standard I was looking for.
So I researched various ways of renewing the lining, including spraying new flock, before settling on flock faced Fablon, stone colour, which I bought online. I first straightened the cardboard by damping and ironing. I then made paper templates, which is quite tricky as the liners are a less regular shape than they look and used these to cut the Fablon to shape. It's sticky enough to grip to the original flock, but not ridiculously so like some products, so accurate positioning is possible, although not without appropriate swearwords. Younger members will probably find it easier, but I was a couple of years too old to be a regular Blue Peter viewer

I think the end result is comparable to new boxes, and £9 of material in comparison to £70 for a new pair!

Haven't worked out how to position photos in the text, but I think every picture tells a story...