Wonderful too to see the return of Vastra, Jenny and a handily resurrected Strax (at the hands of Captain Jack?) We knew from the trailer that they would be back, so presumably, since the mysterious Clara can have no family, they are being brought in as a recurring Scooby Gang, like Rory and River, or the Tyler family. "They're back for the same reason as River came back," Moffat told me, "which is you have something that works so you do it again. And everybody seemed to want to see them again, and I loved writing them. I had unfortunately killed Strax off the first time he appeared, but it's Doctor Who, that's always reversible."
Thanks for sharing that Amoebas!