Thanks LenT.
My lad has been car racing for a good while so we have quite a bit of kit including a NOCO Boost Sport for starting up cars with no charging circuit. It's been really good, always got things going.
Before that I had a Pitking which it think was better, I swear it had more power than my baby grand daughter's lungs. Sadly it had no polarity protection, someone wrong connected it and fried it........
Cheers all