If you log in to your BAEC account on the ba.com website, then go the book flights bit you should see an option 'lowest earning tier points' under class of travel, which gets you the 20tps each way without the £400 price tag of a full J class business ticket... fairly limited availability on each flight though... one of the other kind FTers on this forum may be able to check expertflyer.com for you if you ask nicely and post the dates/times you're travelling...