For reasons best known to themselves, the college technicians decided to upgrade the software to a newer version and [complicated problem you really don't want to know about] meant that it no longer worked either in the college or on my computer at home. Anyway, all is now OK (I think) and I can start making forward progress again instead of hopeless flailing while searching the internet for ever more complicated fixes.
It was such a relief when it finally worked that G and I both cheered! After that, I just did a bit of pruning of the blackberry bushes -- yes, I have learned from Youtube how to prune them properly rather than just randomly slashing them down -- and put the dinner on to simmer.
I have now stopped work for the day and will soon be enjoying said dinner with a glass of wine.