So lately I’ve been watching Doctor Who from the start and earlier this week I got to a 1964 episode called The Waking Ally. I’ve seen it now and I cannot figure out who the waking ally is. So very, very foolishly, I looked it up.

It’s days later and I’ve spent a ludicrous amount of time delving into Doctor Who trivia. And as a consequence, I’m experiencing what I can only describe as double-decker nostalgia. Two layers of nostalgia. I’m apparently nostalgic for a moment when I was nostalgic.

For in October 1964, around the time of this episode I’ve just watched, the cast and crew of Doctor Who had a party in the Bridge Lounge at BBC Television Centre. They were there to celebrate having made 50 episodes.

And thirty years later, I was there too.

It’s not as if I stood there, too scared to mingle, too young and timid to interrupt Verity Lambert talking with William Hartnell. But it felt like that’s what I was doing. Just for a few minutes, I sat on the side of a table in that room, quite possibly where they had sandwiches three decades before me, and I listened closely to nobody’s conversation, I heard nobody give a speech.

And now, today, there’s no Bridge Lounge.

It’s gone in the sense that this part of BBC Television Centre has been demolished, but scarily also in the sense that I couldn’t remember quite where it was. I used to walk by it every evening I worked there, every time I headed for the restaurants. But I have a 1950s architect’s sketch of the building and I’ve been staring at it, completely unable to identify the Bridge Lounge.

Brilliantly, however, Google Maps documented the building before it was demolished and I’ve just been using that to walk around this deeply beloved place. And despite not remembering where the Lounge was, not being able to pinpoint it on a map, “walking” through the building, I went straight there.

It even looked as if I met me coming back.

TVC in Google Maps has ghosts like that figure all over the place, but frustratingly, it isn’t complete. In this case, it stops just short of where I want to go now, where I went before. It takes me up to the bridge part and there’s a sign over the entry saying Bridge Lounge, but it won’t let me go further along that part or then left into the room itself.

But zooming along up to that point, racing faster as I realised that I was right about where to go, I could taste the air in that corridor.

I’m nostalgic for the atmosphere you can’t see, for a party I was thirty years too late for, and in a building that no longer exists.

I still don’t know who the waking ally is, but I’m grateful for the journey he or she has sent me on.