I can confirm that it is looking very good for the new nest site on Riverside Tower, after seeing them entering it in December, and seeing the egg scrape made on a visit later, further proof of acceptance came again in the shape of the Falcon visually entering the nestbox in January.
No doubt she was egg scraping again, other news is that last year's Juvenile - colour ringed ABB, now a 1st winter has made it into the New Year and is still present.
On my latest visit in January, I could hear them calling on Victoria Tower in semi darkness, hard to tell how many but it became apparent as soon as the light grew.
Eventually it revealed not just our pair on Westminster Abbey but also ABB, additionally prey had already been taken. It’s possible that it could have been cached prey taken during the nocturnal hours, something like a Woodcock, or just as well it could have been a Feral Pigeon ambushed leaving roost.
It also showed the commitment of a Falcon, once a mother always a mother, she was feeding the little male! I have seen it before, rather than release the prey to the little fella, she feeds him as well as herself.
The Tiercel as usual didn't get a look in, she finally cached what was left and then guarded it on the Abbey for a couple of hours, the Tiercel again forced to hunt.
It remains now if the adult Tiercel will allow ABB to stay, it is unusual for previous years young to stay, it’s always males it seems, however as breeding fast approaches the adult Tiercel could well become aggressive towards his offspring.
I saw this at Battersea Power Station many years ago.
We will see.
Falcon feeding ABB, Tiercel looking on