I was about to say the same - you got there before me.
It may sound pedantic, but it's important to know because otherwise you could be told that your booking has been TCP'd and think that as a result your companion will be assigned a seat whereas that isn't a sufficient condition, only a necessary one.

I'm sure there was a thread ages ago in which someone provided a step by step guide to read out to clueless agents about exactly how to get a seat assigned for the travelling companion of a Gold.

Now, I have a question about what is means to TCP a booking without seat assignment. This is more than just "putting a note" in the booking", is it? Do seating control actually notice in practice? I ask because I've got an upcoming flight with my partner in CW but we're on separate PNRs as we have to fly back at different times? Is it worth TCPing the bookings even though I can't get him an advance seat assignment? I will try to get us seated together somewhere nice at OLCI (I suppose I could rant about the BA seating policy on here first as is traditional in such situations, but I thought I'd spare everyone that) but I don't want to us then moved about separately. In particular, I'd like to make sure if the flight is full that I'm not upgraded to F away from him and in return he's not downgraded to WTP away from me .