I e-mailed BAEC in Nov '01 about this and they replied:

Each Executive Club transaction you make will extend the validity of all
the miles in your account. A transaction is any time you earn miles
with British Airways or our partners, any time you spend miles on an
Executive Club award, or any time you earn bonus Executive Club miles.
Each new transaction moves the expiration date of your miles ahead 36
months from the date of that transaction. Therefore, your miles may
never expire.

One easy way to earn tier points on BA while paying rock-bottom coach fares is to fly on American (not transatlantic) and try to get bumped. For example, last week I was traveling in L (having bought the ticket on AA.com I was later disappointed to discover this fare does not accrue miles). But when one of my AA flights was oversold I immediately volunteered to get bumped and got re-booked in Y (eligible for miles + tier points). Also flying from the east coast to HNL I missed a flight (despite arriving 3h early due to a long, long check-in line) and was re-booked from N to Y, thus earning tons of tier points. So far this has got me 245 tier points in 1 year.


[This message has been edited by CharlesMD (edited 05-01-2002).]