B5: Centauri makeup

[Reverend]

Probably, yes. Deeds of ownership tend to be kept safe and 1888 isn't THAT long ago, only a generation or two out of living memory. Not when you consider that the Doomsday Book dates back to the 11th century. Trust me, us Brits have mountains of old documents.
Of course the likelihood of finding a record in increased by the fact that whomever he was, Mr Sebastian appears to be reasonably wealthy for the time and there's allot of residences in the west end from that time that are still standing (though I'm pretty sure the actual address is fictional) if he had been living in the slums then obviously finding a record would be next to impossible.

 

[Harvey]

Mountains of old documents, sure. But how easy is it to find the one document in the mountain of documents that you want immediately? It's possible digitization might speed this process up considerably, though. Like has been said before, a minor quibble. Come The Inquisitor is a great episode.

 

[Starscape]

Well it's just information, no?

True, but what I wonder is, does that info even exist at all? I mean, right now, could someone find a record anywhere of who lived at a particular address in London's East End in October 1888? Seems like a longshot. And to have Susan react with a quick "not a problem" seemed odd.

It's be reasonably easy to find such data for a census year (i.e. 1881, 1891...), but probably not for that specific date.

 

[Reverend]

Well of course it's all been digitised by then, that process is already well under way as the physical documents won't last forever.
It should also be remembered that Susan said "no problem" after Sheridan asked about 19th Century English Earth records. When he gave an address, a year and a name (first or last) she got a pained look on her face and said "this may take a while".
So as I said before, it wasn't exactly at her fingertips and it would take an extensive indexing search and a little digging, but it's certainly plausible.
As for a specific date, it's easy to narrow things down when by cross-referencing various documents. The deed of ownership for the house, A missing persons report from Scotland Yard, a record of auction when the house and it's contents were auctioned off or a last will and testament when his family claimed his possessions. Any number of documents can be used to build up a picture with surprisingly little to go on.

You'd be surprised what's out there for the finding. For example, in my aforementioned family tree research, using only the internet I found I was distantly related to an old 20's hollywood actress called Lucy Beaumont and that's just with informations that's publicly available.