If I recall, Dave Edgar's only claim to fame is that he created a most uncomfortable moment for Gerry McCann and Jane Tanner during the farcical reconstruction which was filmed for Ch4.
His opinion of what happened to Maddie is just as much a pissing in the wind as anyone else's if the last ten years is anything to go by.
The Edgar and Cowley Team never provided any breakthrough in the disappearance so his opinion is just that, an opinion.
Thirty + years in the RUC and Cheshire constabulary would perhaps give him slightly more experience of facing downwind when pissing in the wind than most of us would ever hope to have.
His experience of searching for Madeleine McCann in the Algarve possibly had more in parallel with his experience of Northern Ireland badlands while a serving officer with the RUC ... although he would have had no firearm for protection when working in the Algarve.
If Madeleine was kidnapped as Dave Edgar thinks she may have been he will have a fair idea of the type of individual capable of performing such an outrage.
Kidnapping was very much a tool of the trade used by a variety of perpetrators in his younger RUC experiences ... so give the man the respect he is due ... if he says he thinks Madeleine McCann was a kidnap victim ~ and more importantly, that she may well have survived and still be alive ... I think it is well worth giving his informed opinion the consideration it is due.