1: Don’t do it 2: Establish when RH begins at your station and catch a train ten minutes before that. Otherwise you are doomed to let two or three pass before adopting the ‘may I tuck myself under your left armpit?’ approach. 3. Avoid changing lines even if it means a lengthy walk as you are now firmly in RH and will be back in situation 2. 4. As you are now probably on the wrong side of the Thames, you will find that my previous advice on stopping dead in the face of approaching massed humans is no longer valid. The rule on London Bridge seems to be: one south-facing humanoid may walk on the left while fourteen north-facing humanoids form a solid block coming the other way. Unless you stray into the path of the opposition you will probably survive. But beware ‘exiting’ situations when your lane may be crossed by north-facing persons heading for the steps at the end of the bridge. Stopping may be the only option, but remember the coffee-carrying phone-zombie immediately behind you who will fail to notice your brake lights. Don’t mention it!
Instructions you don’t expect to receive while crossing London Bridge at 08.00 hours include: ‘Prepare for the marriage of the lamb’.