I did not receive an email about an upgrade but I did see an offer in the manage my booking screen. If I take it, will I get credited for the business class or would the SUO rules also apply and only give me the economy credits (on BA Exec Club)?
Someone has reported getting Tier Points according to Business when crediting to BAEC about a month ago, although standard procedure is that you would be getting Avios and Tier Points according to your original fare bucket so I would suggest not to rely on Business Tier Points in this case.