How to make Worcestershire sauce

Mark and Bruce posted a recipe for Worcestershire sauce recently and I, true to form, am taking a few weeks to get around to trying it out at home.  I have choir rehearsal all day next Saturday so it's likely that I won't be able to get to the spice shop until the week after.  I have a few days off towards the end of June so I am putting it in my diary for then.  Anyone care to join in on a cook-along?