That's it really. I googled and the only two suggestions I found were to reboot and to adjust the brightness! Tried both but no joy.

Is this on the supplied Apple charger?

Some people are finding iPhones (at least) now refusing to charge on some 3rd party chargers.

Yes, proper apple charger that came with the ipad.

Silly question - is your charger OK?

Those semi fictional electrocutions from 3rd party chargers meant Apple went ahead and stopped every unofficial one they could from working.
I'm not sure what method they used here so it could well mean that some official ones will be failed too.

All a bit strange as I usually trickle charge all my Android devices with the one low power 400mah USB charger.

Why on earth would you think that?

Close all apps (not just minimized), press the home and the power button and hold until you see the Apple logo and let go. Once the iPad restarts go into settings then into general and then reset and then select "reset all settings." Then turn off the iPad by holding just the power button down until the power off slide indicator comes up. Once it is finished shutting down (after the spinning indicator goes away) go ahead and restart the iPad. Then check to see if it will charge. You should see a little lightning indicator next to the battery level. If you don't then I suspect you have a faulty charger and/or charging cable.

Confirm the method and I'll tell you.

You're the one that made the claim.