Light, strong and cheap, please.

Not Chris King.

Is there something there I can't see?

I assume you mean an E2 Head Tube, like on a Trek.

You're going to need a Cane Creek ZS XXC or a Cane Creek Frustrum with a reducing crown race. They're hard to get hold of and they're expensive, around £90. There aren't many options at all.

If it is an E2 head tube, don't make the mistake of thinking you can fit a regular 1.5" headset in the bottom, the Internal Diamter is bigger. A regular 1 1/8" integral headset should fit in the top. There's a useful sheet on the Hope website that shows all of the head tube standards and measurements.

Hope are allegedly bringing one out but I don't think it's available yet.

Good luck with finding one, it took me ages just to get the reducing crown race for the XXC Headset on the Session 88 I've just built, and I had to pay £30 to get one from the States.

Cane Creek are making all of their upper and lower cups available seperately these days. So you can build the headset you need.
You can buy the parts you need to build a custom headset for any bike.
Check out your local stockist.

It's possible to get the Hope 1.5 reducer bottom combined with a standard Hope top headset, just not advertised… 18 Bikes can supply them this way.

But it won't fit the E2 standard headtube.

I just got one of these for my new tapered head tube frame

http://www.freeborn.co.uk/mythic-munro-headset-2011

It is traditional 1.5-1.1/8th lower cup and zero stack 1.18th upper so will work with a normal steerer tube in a tapered headtube. Don't know what they are like but the Cane Creek ones are not available at the moment, hope don't make one and the Chris King one is £180!! So very limited choice unless you buy 2 headsets and mix but that will be silly money.

If the Mythic headset is of a similar quality to their framesets it will be a top drawer item.

"But it won't fit the E2 standard headtube."

Why not? Unless I'm wrong E2 is just the standard 1.5 bottom race, and you can mix and match the Hope headsets all through the range so use whatever top one is appropriate, or whichever of their 2 options for bottom reducers you choose.