A few years ago I purchased a colllection of 10p booklets with spectacular light green doctor blade flaws running horizontaly across the top of the 1/2p values.
Although doctor blade flaws are not catalogued they are highly collectable and add a little something extra to other variations of these booklets they also look stunning when mounted on album pages.
Recently I have sold a couple on eBay and they were greatfully recieved by the new owners who informed me they were very pleased with their purchase.
The auction is for a complete 10p booklet with error of print in the form of a nice horizontal flaw in the form of a light green line in the same colour that is used to print the 6p values. The middle of both 1/2p Machins is affected. The booklet is SGFA2 perf E1 inscribed March 1976.
The flaw I am told occurs as a result of either a faulty doctor blade or more realisticly a bit of grit deposited itself on the blade from the 6p cylinder during the printing process.