Though he was a well-known celebrity photographer in his own right - mostly famous for his "creative" portraits where he had subjects pretend to be a table leg or stick their heads through a toilet seat - he definitely fell in the realm of "commoner" as far as the royal family was concerned, and that made theirs the first marriage of royalty to a commoner in roughly 450 years. They even had to invent an earldom for him (the Earl of Snowdon) when Margaret got pregnant, so the royal baby wouldn't be born without a title and doubtlessly get picked on by all the other royal babies.
Here they are on vacation in Arizona. All the fences made it easy for Snowdon to disguise his height.
His marriage to Princess Margaret was "like Cinderella in reverse," according to rival photographer Nicky Haslam. But Tony didn't think it was such a big deal. Not only did he flout royal customs like walking two steps behind his wife in public but normal human being customs as well, like not cheating on your wife with other women and particularly not cheating on your wife with other men.
Moments later, he gave a "royal edict" to the cameraman in a nearby broom closet.