First, obviously, Oriel Chambers is a fantastic building. Nothing I say here should be construed to mean that I think anything else.
The word “skyscraper” is quite subjective, and a lot of the pointless debate about which building is “the first skyscraper” boils down to an argument about what that word means. Since there is no generally-agreed upon definition, one person’s take is as good as another, so here’s mine:
(1) A skyscraper has to be tall compared to its context. I don’t know if a five-story building was particularly tall for central Liverpool in the 1860s, but I’d guess not.
(2) A skyscraper has to have useable floors to justify its height, otherwise it’s a decorative tower or obelisk. Oriel Chambers uses its height.
(3) A skyscraper – as opposed to a tall building – should have some degree of modern technology in its construction. The big windows on the street facades required modern glass-making, and Oriel Chambers has more interesting metal-supported walls facing its courtyard, described (in Wikipedia, anyway) as “rely[ing] on H-section iron columns at the perimeter, which support the floors and cladding.” So this criterion is a yes.
Here’s a similar building about the same age, the 1857 Haughwout Building in New York.
It’s also five stories tall. It’s a little hard to see in the photo because the windows were filthy when the photo was taken in 1968, but it also has very large windows for its era. The two street facades were, with the exception of the sheet-metal and wood cornice, entirely cast iron. So it, like Oriel Chambers, meets my criteria 2 and 3 above, but not criterion 1. The cast-iron structure of those street facades supports the floors and cladding as well, so it’s not clear to me how Oriel Chambers is closer to modern curtain walls. I used Haughwout as an example not because it was ground-breaking, but specifically because it isn’t: it’s the arguably best-looking cast-iron facade extent in New York, but very much middle-of-the-road technology for its era.
There’s no sharp line between big and tall buildings of the early nineteenth century and those that were part of the skyscraper boom of the 1880s and 90s. Architectural historians have called a number of buildings “proto-skyscrapers” because they meet some but not all of those historians’ personal lists of criteria. In my opinion, the big buildings in New York with cast-iron facades (including Haughwout) and a lot of experimental buildings constructed all over the world (including Oriel Chambers) fall into that category. They were individual steps forward – and some sideways and a few backwards – as industrial technology was being used in buildings and influencing their architectural design. That’s not meant to belittle them: every step in an evolutionary process matters.
My discussion of skyscraper technology at length, The Structure of Skyscrapers, discusses tall buildings from the mid-1870s onward because I tried to stick to the “tall for its context” criterion.