NavList:

The Heading/Speed Acceleration Error Card, Stores Ref 6B/3677 was designed by an RAF Navigator called Ted Mears who subsequently became O/C No 44 Sqn.  It was used with a Computer Dead Reckoning Mk 4A or Mk 4B.  Within the RAF it was known as ‘The Mears Slide’.   

I’m ashamed to say I converted my first one using lots of Snowpake to make a height of tide slide for my Mk 4B, but I managed to scrounge another when I got interested in celestial again.  This is my only one.

I can think of three ways of getting one:
a.  Try asking London Name Plate Mfg Co Ltd of Brighton, England if they have one left in their cupboard.
b.  I colour photocopy mine and send a copy to those requesting a one.
c.  My son has promised to scan a soft copy at work after the holidays; I could email the soft copy to those requiring one.  If it works, I favour this method.

Once received, the copy could be stuck on thin plastic or aluminium, or you could draw your own; all the lines are straight ones.  DaveP