Submissive dog

[insanityscratching]

Eric has since a puppy got down on his tum on sight of a dog. He has doggy friends that he plays with on his walks and no longer gets down with them because he is familiar with them I suppose.With dogs he doesn't know he gets down until either he can't see them or until they have come over to say hello and then he will happily greet them and play if there is an opportunity.
He has never been snapped at by a dog and he will happily play and chase with any available dog and he's never snapped at a dog either. The crouching and crawling wouldn't be a problem if he only did it to approaching dogs. Trouble is he does it when he catches sight of a dog on the other side of the field that has no intention of coming over and won't budge until it's out of sight.
Is there anything I can do to hurry him up a bit because even the tried and tested ham and sausage don't get him moving?

Hard to say over the internet but my first reaction is that he is fearful so I would treat him like a reactive dog.

Don't get too close to any dog - this may mean you are football pitches away from other dogs but reward him when he is not reacting so before he goes down on his belly. Turn away in a positive manner and reward him for being a brave boy by walking away from the other dog. As he realizes there is no pressure you will be able to make the distance between the dogs smaller

Thank you I'll try that. He's ok when on the lead walking on the road and passes other dogs on leads with nothing more than a sniff and a tail wag it's when either he is off lead or he sees or suspects that the other dog is.
One of his best buddies is the farmer's sheepdog who he plays with in the fields and who rounds him up like a sheep so could some of the crawling be that he suspects that it's Meg and he's trying to initiate a game? Meg does appear at random, not always with the farmer but she has been so lovely and patient with him since a pup and he loves to see her and I wonder if that's why he only does it in the fields where they meet?

Our black lab sometimes glues himself the ground when another dog approaches, but he doesn't show any sigs of distress/fear, and seems to be waiting for the other dog to approach for a quick sniff or play. It's his way of signalling I'm friendly play with me. If you google its fairly common behaviour especially in young dogs, it will depend on what other behaviour/body language Eric is displaying if he is being friendly or fearful.

His tail is up so I think that he's waiting for them to come and play, he's really friendly if a dog comes over, happy to chase and be chased.It's just that not every dog we spot is going to come over and play I suppose, mind you at least he doesn't go bounding over to unknown dogs who might not want to play so I suppose it's a positive. We have been incredibly lucky tbh because when he was a pup we met quite a few owners and their patient and tolerant dogs who taught him to play nicely without being rough when he overstepped the mark and we still meet them to play now he's got better manners. Meg was always fantastic at bringing him back when he was a petulant teen and resisting recall