On page two of the story, panel one is clearly drawn by Frank Springer (the credited artist), who also drew the splash page. Springer's more naturalistic figures are replaced by work more closely adhering to Jack Kirby's style, with broader and more exaggerated characters. The lettering also changes in panels 2-4. Artie Simek's simple, distinctive style is replaced by a less precise look, the work of staffer Morrie Kuramoto, who was usually called on to do correction work. In panel 4 another letterer takes over, Jean Izzo, the daughter of Artie Simek, who also lettered for Marvel. It's worth noting that Johnny Craig, credited as inker on the splash, also inked the Barry Smith pages. Since the inker is one of the last in the production line, these pages were likely pasted in and included with Craig's other pages.
Page 3 is a complete Smith page, inked by Craig and lettered by Izzo with corrections by Kuramoto. One can see the Kirby-style dynamism that is not part of Springer's work. In fact, Springer was attempting to follow Steranko in panel arrangement and style more than anyone else. Aside from the jagged panels, Smith is copying Kirby more than Steranko on these pages.
Page 4 features Smith art only on the first two panels (or three panels if you include Fury's face as a separate panel); with perhaps John Romita touching up some figures in panel one. We then segue to the section we left off, with Fury walking through the streets of New York. Springer returns, as does Simek's lettering.
Nick Fury, Agent of Shield # 10 is cover dated March 1969, which coincides with Barry Smith's first credited work for Marvel in X-Men # 53. The Bullpen Bulletins that month notes:
"Everyone's talking about bashful Barry Smith, the surprising new staffer we just imported from merrie ol' England."
They go on to mention his work on the current X-Men and an upcoming issue of SHIELD. Smith did draw a full issue of SHIELD only two issues later. but was this his first work for Marvel, or were these pages produced later than the X-Men story? Judging from those few pages, I suspect they were drawn after the X-Men. They are certainly crude, but look a bit more confident in presentation. Were these pages a test to see if he could draw SHIELD on a regular basis? Were they purposely inserted into the Springer drawn story?
I went to one of the sources around at the time. Roy Thomas had this to say:
"Afraid I don't recall anything about why Barry would have been called on to draw a couple of pages' worth of that story... but it certainly wouldn't have been just to 'test' him. It must be that, for whatever reason, Stan (and he would definitely have been the only person to make that decision at that time) must not have liked Springer's depiction of action and tried Barry out on jazzing it up."
I opined that perhaps the two and a half "missing" Springer pages had Fury walking through the streets of Manhattan, lost in thought. When Springer's art resumes, Fury is still outside, so the lack of action may be a possibility. I'l take another look at the later pages to see when any action takes place.
It's an interesting mystery, and a little known footnote to the early work of Barry Smith, who would go on to make a name for himself illustrating the adventures of Conan the Barbarian, where his artwork grew into a lush, detailed style that gained deserved attention. Still, his early work had a sense of enthusiasm that translated to the printed page, something that Stan Lee and Roy Thomas recognized from the start.
To view some of Barry Smith's earliest work. pin-ups published in the British weeklies, go to Kid Robson's site on my blog list. You won't be disappointed!