If you thought my account of the trade day at BRI was dull you ain't seen nothing yet.
One of the lecturers happened to mention that acetic acid is normally found in beer at a level of 130mg/l. This lead to some hasty calculations shifting decimal places on my part, and as soon as I got home a consultation of my acidity to pH ready reckoner.
130mg/l = 0.13% which give us a pH of 3.82
This fits in well with my previous calculations and gives further confirmation I've got my figures right.