Got the call back last night from someone in "Customer Advocacy" at Citibank, and he relayed a few things:
* He went to lengths to try to ensure I understood the difference between an enquiry (where you make an application for credit) and an access (where Citibank just looks at the data).
* The first access in May 2007 was Citibank's Business/Sales section looking to see whether they should target me for additional services or offers (which would involve further credit approval. Perhaps they were running offering things "pre-approved" - I am hypothesising that "pre-approval" might induce people to be more likely to sign up.
* The second access in June 2007 was Citibank's Risk Assessment arm, checking to see whether I had any defaults or otherwise which they were unaware of.
In the discussion, it came to light that Citibank does run these sorts of programs regularly, and likely they will in the future.