No sparks

I discovered two days ago that the battery on my Royal Enfield was completely flat . I bought it new about a year ago and have had no problems until now. I'm not amused to have it on a battery charger , that's what alternators are for. I don't think I left the ignition on since my last ride on it a month ago. I hope there is no issues with the regulator / rectifier . That 6v /12 volt battery charger I paid 50p for at a car boot sale many years ago.  It's old and all it needed was a new plug and two crocodile clips and a lick of paint.