Over and above what the pink CAA form says. So this 20 minutes does not apply to those of us who use Sword or Cirrus to uplift fuel.
I disagree completely with that statement. The fuel figure that the flight planning system throws up is a minimum (subject to any slight adjustments) legal fuel that you may depart with. The AIC is saying that in addition to the legal minimum you should carry some additional holding fuel when inbound to busy airfields in the UK. It's not a legal requirement they are simply giving advice.
As for fuel leagues it beggars belief that a company such as BA that prides itself, quite rightly, on it's flight safety standards still uses these.