Looks a doddle, Acapulco. 
BUT it DOES say "Hammerite Metalmaster produces low overspray, but before spraying, mask off areas such as windows, window frames, doors, pipes, patios, plants etc. to protect them from overspray, including surrounding property. All metal items that are not to be painted must be removed from the work area or protected. "
Including surrounding property ??? 
Does that mean if you & I had adjoining properties & you painted yours I'd get a freebie ? As my OH said it would be great for spraying our grilles from inside if it worked that well. Take windows out if you can, never had much luck removing ours in some.
Go on, have a bash.