Brian,
In this eternal debate about what is and isn't soul, one of the most interesting things to look at is the Bill Board and Cash Box Soul / RnB Charts from the 60's.
Remember, these charts were based on what the BLACK AMERICAN listening and buying public were getting into at the time.
Very few WHITE AMERICAN artists , let alone white artists from outside the US , made the Soul Charts from 1964 on.
You can bet that if a "pop" record made the soul charts around that time, then black radio DJ's and black listeners were accepting it as bone fide SOUL music. In a sense, this was the ultimate accolade!
When Tom Jones' "Its Not Unusual" was first released in the US , it instantly received heavy rotation on black radio stations and it duly shot straight to the upper reaches of the Bill Board soul chart. Their black listeners thought Tom was black !!!
So much so that Vee Jay Records immediately rush released a cover version of it by the greatest soul group of all time, the mighty mighty Dells !!! Tom's original won out of course and smashed to the top of pop and soul charts , and the rest, as we say , is history!
But note that , as soon as Tom toured the states , and black radio DJ's realised he was white , they dropped it ....
As I say, everyone should take time out to look at these soul charts and you'll see why acts such as the Righteous Bros and the Young Rascals had several soul chart entries. These acts had real soul credibilty among black listeners.
Even a couple of the Stones' early big hits like "Satisfaction" made the soul charts !!! Spencer Davis Group "I'm A Man" went high on the Soul charts in '67 ... and so on.
And the same principle applied in the 70's when the US soul music scene and black culture was reflected by the legendary syndicated TV show "Soul Train". The first white pop artists to appear on Soul Train were David Bowie and shortly after Elton John - Philadelphia Freedom is a fantastic homage to the Philly Sound !!!!
Make your own conclusions !