Huh. Is there any obvious way to get a higher vantage point short of breaking out the wings?

Not especially, but the traffic is a lot thinner down that skeevy-looking side alley, and it has some fire escapes he can climb.

Cam will go ahead and climb the fire escape, why not.

Lupin gives him a bemused look but doesn't say anything. 

When Cam looks out over the edge of Diagon Alley, he can see a couple of smaller magical streets, and then Diagon Alley again, complete with this building and the back of his own head.

...he waves at himself, blinking, and then climbs back down. "Space warping is weird," he remarks to Lupin when he steps off the last rung.

"I suppose it is, yes. Very useful, though. I believe you wanted to go to Gringott's while we were here?"

"Gringott's? Is that the bank, I wanted to go to the bank."

"Yes, that's the bank. It's this way." He gestures and sets off. "In case nobody told you: Gringotts is run by goblins. They're not very fond of wizards, for pretty good reasons. Don't stare, and if they're grouchy it's nothing personal."

"Good to know. Am I correct in assuming that at least until I have my bearings well enough to want to do major infrastructure work of some kind the basilisk alone is going to be worth enough for walking-around-money purposes and I do not need to investigate whether they'll cash conjured materials today?"

"Yes, it should be plenty unless you're planning to buy a giant house in London and similar. Here we are."

Gringotts is a massive white marble building, with large imposing doors flanked by short imposing pointy-faced guards in shiny uniforms. There's a poem on the doors promising unspecified dooms to anyone trying to rob the place.

Cam tries not to stare at the pointy faces. He reads the unspecified dooms. He sweeps into the bank, fishing for his IOU.

There's not much of a line on a weekday morning; he can go right up to the counter. The teller says, "What's your business?" in a slight accent probably caused by his pointy teeth.

Cam hands over the slip of paper. "This is! I'll probably need to open an account about it."

The goblin inspects the slip and says, "Here's the new account form," pulling a sheet of parchment out from under the counter. "There are tables with quills over there," he adds, pointing at the other side of the room.

"Is it necessary to use a quill?" Cam asks, looking at the form.

Suspicious face. "Any legible method of putting ink on the form will suffice."

Cam starts filling out fields without making use of table or quill. He will only be stumped if they want any really obscure information, like, uh, "address".

The teller looks vaguely disapproving but this is not against any actual rules. The form wants his name, address, date of birth, employment status, occupation and employer if any, and to know whether this is a personal account or for a business; if the latter it wants to know a great deal of other stuff. Also, does he want to let anyone else access his account, and would he prefer access to be controlled by a key or by providing a drop of blood every time he wants to make a deposit or withdrawal. 

"Can I add my own security measures in addition to the key or blood? Also, is 'Hogwarts' a sufficient address, and how quickly will you wish to be notified if that changes? Also, if my birthday appears on casual inspection to be a date which occurred five years ago, will there be any problems?"

"Any security measures you add yourself must be inside your vault and unable to affect patrons outside it. Hogwarts is an acceptable address; if it changes and you don't notify us any letters we send you may be delayed. Were you born five years ago? Falsifying information is subject to fines and, in certain cases, the seizure of your account."

"I am not five years old. However, my birth date is in 1987."

"Gone back in time, have you?"

"You could describe it that way."

Apparently the teller was being sarcastic, she raises an eyebrow and mutters something in an unfamiliar language*. "Hmm. Here, sign this affidavit." She hands him an affidavit asserting that as far as he knows, nobody thinks he is their dependent child and he is willing to be considered an adult for all banking purposes including criminal penalties.

*It translated to "Wizards and their weird wizard problems."

He signs the affidavit. "If I do the drop of blood thing does it have to come out of my actual body right then or can I conjure materially identical blood and have that work? Alternately, are the keys inherently magical?"