Did you think Jane Tanner's evidence was reliable? A pair of feet and another faceless man. At least the Smiths saw a girl who resembled Madeleine and was around her age.
The 'significance', the bar to which Davey Gray would like evidence to aspire to, is actually very compelling. As compelling as an eye witness account gets save for a conversation with the man and a dead cert ID.
At about the right time, in the correct location, he saw a man who looked like Gerry McCann carrying a girl of the approximate age as wee Maddie. To compound this account, he's walking directly the opposite direction from the scene where a small child went missing.
Some here like box ticking - there's a lot of boxes ticked right there.
Moreover, if this de facto suspicious character resembled CB I'm sure the significance would be ratcheted up exponentially.
I say again. The only eye witness account that matters in this whole sorry saga.
Edit: I'll go further. If Martin Smith would have come forward sooner the McCann pair would have been charged.