I walk a 7 month old retriever for someone just once a week (I am between dogs myself!). Last time I took him he ran off and joined a group of young Springers. He was having a great game with them and ignoring me. Eventually I had to go to fetch him. The other owner called her dogs off and I managed to get hold of my dog who was on his back on the ground having been in a "play" fight with one of them at the time I turned up. I had to hold him where he was as I tried to get his lead on. Lucky for me I had thick gloves on as he was obviously really hyped up biting at me and kicking. I could not get him to stand just holding his collar he just stayed on his back going for me. I had my knee on him and my gloved hand in a fist in his mouth. Goodness knows what anyone walking by would have made of it. Eventually I got him on his lead and he did get up and just carried on on his walk as if nothing had happened.
Recall is obviously one of the problems but I cannot resolve that as I only walk him once a week...his owners are new to dogs but they are trying hard. But what do I do if he gets involved with another dog again?

Hi, there's a lot you can do with his recall once a week :)

Prepare a bag of really tasty treats and call him back often for one, even when there's no other dogs or people around.  Use the same command every time. 

Basically the law says that dogs should be under the handler's control in a public place.  Since you are the one walking him, and you know he has a bad recall, yet you let him off the lead and then cannot control or catch him - well.....

Either work on his recall so that it improves and he can be let off lead - or you're just not going to be able to let him off lead.                                                         

Personally, I doubt it was necessary to kneel on him and shove your fist in his mouth - he doesn't sound vicious and this just sounds like quite a frightening experience when he was already in a submissive position.  You could have taken him by the collar and pulled him up into a standing position before attaching the lead. 

Thank you for the responses.
I take note.
I would just like to point out in my defence that I did not "shove" my fist into his mouth. I put my hand into a fist as he kept biting at it and held it in his mouth to prevent me from being chewed. I was unfortunately put on the spot at the time and as my own dog was as good as gold  I guess I panicked as I had never had to deal with this before. And I did try to get him to stand up but it would have meant lifting him and he was wriggling too much.
However I admit I could have had better control and I will work on it as I do enjoy getting out for a walk with him.
When I get my new pup we will be off to classes as soon as we can!! Any tips on finding classes?

Yes - where are you based, we might be able to recommend some?

Try: www.apdt.co.uk  for a list of reward-based trainers.

Onetwothree has already given you some excellent recall advice which you would be wise to follow, there are always smaller more vulnerable dogs who would not appreciate a bounding Retriever coming at them, aswell as children and other adults and I also agree with everything that onetwothree has said, especially with regards to the lead attachment episode, not a good way to lead a dog! After all he was still in play mode and probably expected you to have a good rumble with him too, always get a dog to stand or sit to lead them. If he had been in one of these two positions his over zealousness would not have occurred. I can't see that he has overreacted after his play it is just normal behaviour for a puppy and adolescent dog, he just wanted to continue his play being on his back. :-) Lead him correctly and it won't happen again.

As he is only 7 months old he is still basically a baby. A big one, but still a baby ;) I would get a long lead. They are about 20-30 feet long and cost under a tenner, so wouldn't break the bank. This way he can still play, but you will still have control :) My young bitch (now 15 months old) has had to go back onto the long lead recently due a very scary incident with a dual carriageway and lorries and has been very good since she went back onto the long lead. Her recall is much improved, but I don't 100% trust her, so will keep at it. You could try talking to the owners about it, too. They will have to spend time on his recall or any work that you put into him could be ruined. :D

Just working on the recall yourself can work wonders.  I have done it myself only having a dog maybe once a month for a few days.  Walking on a loose lead and all other basic commands can be taught like this also but the little mite may only behave well for you and not the owners who may not be training him.  They soon learn to relate treats and kindness and to the people that provide them.  You may have to reinforce your training regularly but it is going to be worth it if you are to enjoy your walks.