Big thanks to Juan Fuertes, Juha-Markku Liikala , Sylvie Duchateau , Roberto Castaldo, Makoto Ueki and (as always) to JUN.
A few users have emailed me, saying that when they have installed the toolbar they have been unable to activate it from the Internet Explorer 'View > Toolbars' menu. They reported that the accessibility toolbar menu item is there but it is "greyed out". I have tracked down the problem. To solve this issue: