Tomorrow morning, Steven Moffat will host a press conference to introduce the actress cast as Doctor Who's new companion. The timing probably isn't arbitrary – I expect we'll be seeing her film in public places over the coming days and weeks.
As of now, the best info we have comes from Daily Mirror TV section Deputy Editor Mark Jeffers. Here's his interesting tweet on the matter:
BBC source has confirmed to me they will unveil new Doctor Who assistant tmrow. She is "pretty" but "not household name".
— Mark Jefferies (@mirrorjeffers) March 20, 2012
Quite a formulaic choice? Well, we'll have to wait and see.
What this means for Miranda Hart's involvement in the series is also unclear – she's definitely a household name here in the UK – but it doesn't, by itself, rule Sophia Myles out of the running.
Myself, I don't think it's Myles, despite the gathered evidence to the contrary. Moffat has referred to this upcoming companion as a "new friend" and, timey wimey-ness or no, Myles' Reinette certainly had a relationship with the tenth Doctor.
UPDATE: Aisling Loftus is the hot tip on the grapevine. We'll see…
Stay tuned to Bleeding Cool in the morning because, all being well, we'll be bringing the news to you at the very second we know it. In the mean time… anybody got a wish list? Who might you like it to be?