Dry Clean Only Clothing?

[soberton]

I've just been given a lovely Dorothy Perkins Parka style coat and on checking the label, I noticed that it stipulates Dry Clean Only.
It's one of those coats where the fluffy lining can be unbuttoned to separate from the outer shell.
I would normally have popped it through a machine wash just to freshen up, but now I'm not sure whether I should.
Any ideas/tips would be appreciated.

Is it waterproof?

If it has a special finish, washing it might remove it.
It might not be colourfast.

If you are desperate to wash it, hand wash it in lukewarm water using washing powder not 2-in-1.

wash the inner and outer layer separately.

Line dry.

It's khaki, 100% polyester (both the outer and detachable lining).
It doesn't state that it has any water repellant properties, but walking back home in some drizzle today it seems to have shrugged it off.
The label that says dry clean only, also advised a cool iron and has the letter P in a circle.
Just wondered if it would go in a gentle cool wash with non-bio persil?

I was given it so don't know how old it is, but it's in lovely condition.

Does it have any wadding in it? I washed a puffer type coat and it wasn't quite the same.

I'd probably give it a go.
I think you can get a breathable water repellent spray should you need it.

Apart from expensive silk and cashmere, I wash it on a delicate handwash and it's fine.