Ingredients in the UK
Great Feedback from Cherry and Alexis
You gave me useful advice a few years back about flour after I moved to the UK. I've since discovered that McDougall's Grade "00" flour (not self-rising) is a perfect substitute.
Additionally, I find that buttermilk is a better substitute for American sour cream than (higher fat) UK soured cream in cakes and muffins--seems to give more reliable results than an educated guess at the amount of soured cream to decrease.
Thus, with a few added marginalia, the US "Cake Bible" remains in use here.
Cherry
AFAIK, the 00 is not bleached, but it is somewhat softer than the regular plain flour. I researched this once, and according to the Flour Advisory Bureau, bleached flour is not available to the UK consumer. (Although I suspect that the McDougall Supreme Sponge is bleached as it claims it can absorb more fat and sugar than regular flour... sadly it's only available in self-rising!)
UK spoons are now pretty much standardised at 5 and 15ml. The Aussies are the ones who are off: an Australian tablespoon is 20ml! I bake in metric now so I can ignore imperial versus US ounces.
The other headache is baking powder. I know a lot of Americans who report having to use 1.5x as much. My guess is that there's more bulking agent--the first ingredient listed on the container is rice flour. I'll be honest, I cheat: I bring American baking powder back with me (and I've got some Swans Down as well).
British soured cream is the same fat content as American, 18%, though it tends to be thinner in texture. I've never had a problem cooking with it.