Firstly, I'd like to thank metro074 (thanks, Carol) for her User Award on my Golden Chalice Vine, and to everyone who voted and commented, it is really appreciated that this series is finding favour.
I found this beautiful lily at Staunton Country Park in Havant, Hampshire, and have yet to find out its name. I think it's probably an Oriental hybrid, but it was its large size that attracted me most, and the hoverflies that were attracted to it, as well as its yellow stripes and red speckles.
I will keep searching and see if I can find a name for it.
Of course, if anyone knows it, I'd be grateful for an ID.
PS: I've found it! It's an Oriental hybrid lily called "Lovely Girl", renowned for its very large, exotic, intensely scented, upward-facing blooms.