Foreign Earned Income - Include taxes paid to UK Government?

When I'm reporting my foreign earned income, do I use the pre or post-tax amount? For example, which of the following would I use to calculate "Wages From a Foreign Source"?

1. 50,000 GBP * 1.84
2. 50,000 GBP (total) - 15,000 GBP (taxes) = 35,000 GBP * 1.84

PRETAX!  You then take the Foreign Earned Income Exclusion and/or the Foreign Tax Credit to reduce the US tax to a small figure, hopefully zero.  Use a tax programme so that you can run several versions of your return:

1) with just the Foreign Earned Income Exclusion on Form 2555
2) with just the Foreign Tax Credit (that's where you put the 15,000 GBP in your example) on Form 1116.
3) with both FEIE and FTC (the FTC must be adjusted on form 1116 box 10 for the FEIE).

Whichever gets you the best result, use.  Note:  This assumes you are a first time filer over here!