More of the 'fixing stuff'. My weather station, reports wirelessly to the indoor console/display, which then plugs via USB, into RPi to exchange data and provide 5v to power it, to avoid it using batteries. RPi then connects to LAN, so weather data can be viewed remotely/uploaded to weather sites - as it has reliably done for years. Console flattened it's internal batteries, so probably missing it's 5v USB supply, RPi had it's power LED lit, but it's weather website was inaccessible.
A number of unconnected items decided to give up the ghost together, so I only got around to the weather station properly this morning. I tested the console on a 5v USB supply - all working. Plugged that into the RPi on a spare USB wallwart, that worked, and so decided it must be the original USB psu which was faulty. Swapped it out, reinstalled and all now working at last.