An 'unknown alien artefact' had been found in California, that itself had been more than enough to garner the Doctor's attention. What had actually made him hurry to said scene was that the Brigadier had actually specifically requested his help in this matter.
It had rather taken him by shock that his arrival had been expected, all his questions answered and he'd been given his own make-shift lab for his role as official UNIT scientific advisor. He'd been slightly upset that none of the old faces he'd known during his exile were stationed here, but he couldn't expect everything.
The lab wasn't as good his one on the TARDIS, but then very few were and he'd learnt well before this how to make the best of situations. And really, they were trying to accommodate him sufficiently.
He was currently bent over a microscope looking at a sample, adjusting the magnification when he'd heard the kerfuffle behind him. He didn't even shift from his position with a sigh he began, "I know you're just trying to help but really, I don't need an assistant to help me on this. I am rather capable on my own thank you."