[P @ F]

Why can't you just do this like we do on all four of our reels? :

This is exactly what i am using at the minute Simon , never a problem , i only switch to the brass female when the heater goes in as more pressure is involved then .

Perhaps the OP has his pressure too high , hence the popping off ?

[Crystal-clear]

Here is one unscrewed  , the tail is 12.5mm / half inch  , that should go right on the braided hose with the supplied collar or just jubileed up as you have it at the mo .
One of the 2 fittings you see has a waterstop built in , this one may restict flow so i would go with the other to be safe .

appreciate the info mate i defo need it jubileed up i really dont get on with any of the twisting methods . so i think the Gardiner ones are the best around £15 + post but it seems a serious connection sod the twisty stuff ! yes it keeps popping out set at 60 they seem to last around 2 months then deteriorate when that happens they pop out in any pressure even 40!

[Crystal-clear]

I'm pretty sure this would work as well.

http://gardinerpolesystems.co.uk/all-products/pump-hose/hose-fittings-adapters/garden-hose-couplings/quick-release-shut-off-coupling-with-a-hose-barb.html

or this
https://www.ebay.co.uk/itm/NITO-CLICK-QUICK-RELEASE-COUPLING-FEMALE-X-1-2-HOSETAIL-COMPATIBLE-WITH-HOZELOCK/172847346363?epid=1174456519&hash=item283e8132bb:g:se0AAOSwgDxZ0-R1

Thanks spruce yes these are the sort of connections i need ones that are strictly jubilee clipped up  it turns out i raided the shed and found my hose lock plastic connector grave yard can you believe it around 40 hose locks some with valves over a good 10 years+ at what £7 each we talking £280 of waste ? sod that im getting good connectors next time alot cheaper in the long run ...

reason why i raided shed was to find a spare one of those connectors and i actually did only 1 of those and 40 plastic ones says alot! but it must have been in the hoselock grave yard for a reason tested it and it worked so ill ride it out for now