PROBLEM SOLVED John asked several questions and ultimately asked me to send him a copy of my workspaces. I obliged!
The problem turned out to be a little peculiar. Somehow I had managed to select the ‘minimisation’ icon from the icon list that can be exposed on the extreme RHS of the BP/Eclipse window. This had the effect of hiding everything (including the Model Explorer pane and any open element tabs in the central window etc.) To get things back to normal John found that I needed to re-click the minimisation icon and then ‘unhide’ everything. I managed to do the latter by going to the ‘Show View’ option under ‘Window’.
Anyway, the good news is that I don’t have a workspace problem (after all). It had to be something strange that I did. Something I really don’t remember doing! I’m beginning to feel that I should have a continuous video monitoring every action I undertake. :-)
Again, thank you all for your willingness to help and advise. Much appreciated.