To reply to myself, the answer is in the preamble, but didn't realise it
Only the slides that contain a noteitem environment are printed out.
All my other slides had this,but I hadn't added it to the two new slides.
Graham
The preamble for the handout is
%next five lines needed to print two to a page handout. Comment out for
presentation
\usepackage{pgfpages}
\pgfpagesuselayout{2 on 1}[a4paper,border shrink=2mm]
\setbeamercolor{background canvas}{bg=black!1}
\setbeamertemplate{footline}[page number]
\setbeameroption{show only notes}
