What on earth is this bad boy (with photo)?

[Bingus]

Sitting casually on my leg with it's big yellow snout?

Was he stripey? Could he be this chap?

https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/flies/hornet-mimic-hoverfly

No he looked like a massive brown fly with big brown wings and a yellow snout. I've never seen anything like it before.

Wasp mimic hoverfly?

Yeah, hoverfly of some description (possibly Volucella) but impossible to say which without seeing the rest of it.

I think it’s a lady cos its eyes have a gap in the middle.

Google images says you might be right @RagamuffinCat as it has the same yellow nose of the pic I found of the wasp minic hoverfly below. It's didn't look stripy though, unless the stripes were very faint.

I can't tell if you're being serious! Can you actually tell like that?!

I am serious! The males’ eyes tend to join in the middle. I learned that quite recently. It might not be the same for all species but I think it’s the case for the majority.

Here you go: https://hoverflyvision.weebly.com/old-blogg/how-do-we-tell-male-and-female-hoverflies-apart-its-all-in-the-eyes

Well you learn something new every day!