Just searched a bit more...
The ISP Forum from April 2015, roughly 3 months after the one reporting 60-61,000, then reported 64,000 cabinets, so successfully continuing the "200 cabs per week". The forum in September 2015 then reported 69,000 cabinets - a similar rate of progress.
Unfortunately, I don't have any forum slides from anywhere in 2013 and 2014; the last I can see in 2012 quotes 31,000 cabinets as of October 2012.
If the 2015 forums are correct, that would put the 55,000 cab total date around mid-2014 instead ... and that would roughly tie to the end of the commercial work - so it might be a reference to the BT-funded cabs. Some BDUK projects (like North Yorkshire) will have been well into their projects though.
I have gone back looking at quarterly financial reports, and can find nothing there. They only report the number of homes passed - which, IIRC, was running at a million properties per quarter pretty consistently until the latter half of 2015. I guess you'd expect a slowdown as the rural cabs gradually get smaller.
I wonder where else I've seen the figures?
I hope the reference to 40Mbps related to the 2009 milestone, rather than "Today"!