Steve, the Ilex 3 I use behind my 60 Perigraphe may be an anomaly, but according to my and SKGrimes' shutter speed testers it is bang on. There are also large Compound shutters.
Ian, there's always ebay.com and USPS. I fully appreciate the risks of dealing with distant strangers, but sometimes the risk is worth taking. I've bought photographic equipment from the UK, even imported a car from the UK. The car was a Scimitar, bought sight unseen with help from an RSSOC member.
One thing to be aware of with respect to Ilex 3s. I've recovered three from oscilloscope cameras, sold two. 'Scope camera Ilex 3s' rear tubes aren't threaded externally, so the usual way of holding the shutter on a board -- clamp the board between shutter and retaining ring -- can't be used with them. 'Scope camera Ilex 3s with 75/1.9 lenses have restricted apertures. To get full aperture when front mounting, those shutterss diaphragms have to be removed. The one I use behind the Perigraphe is held to the board by screws that go through the board and into the shutter body. On the whole, 'scope camera Ilex 3s are poisoned gifts.