Thank you Phil - yes, it is my flight that I got the date changed for.

I took your suggestion. Phoned BA and a gentleman checked my booking and said that everything seems fine with it. He put me through to web support who checked my reference and said that the flight appears not to be open yet (despite it being less than 24 hours before departure - 1.30pm tomorrow afternoon - AND MMB saying that my flight is "now open for online check-in"...). He said that "although normally OLCI automatically opens at -24hours, sometimes online check-in is held back by the airport", so I should try again in a few hours...

Bit odd really and - if anyone from BA web technical support is reading it - a bit of a bug. You really want something to tell you to this affect and not just kick you back to the MMB page without any clue of what is happening.

Am not too bothered - we are on the flight and there are no such things as truly bad Club seats (currently in 11A and 11B on a three class 777 - which are ok seats, assuming no little screamer in the bulkhead behind). We are getting to Heathrow just over 3 hours before the flight - so plenty of time if we have to use SSCI...

Boo