Aggression towards particular dogs

[bex_a_stead]

I have a golden retriever, which has had three separate incidents with different Springer Spaniels:
1. As a puppy he was chased by one
2. He was attacked by one being protective of a bitch in season
3. He was attacked by one resulting in being bitten on the nose, for which he still bares the scar.

On a normal walk, he loves to play with other dogs and on seeing a Spaniel this morning he took an initially playful stance, however, when we got close to the Spaniel, he went for it.

It probably sounded worse than it was, but it wasn't nice. He's never behaved like this before and I don’t want to see this behaviour again. What steps should I take to prepare for meeting another Spaniel on our walk (which cannot be guaranteed on a daily basis)?

The other issue here is some friends of ours have a Spaniel and are coming to stay in a few weeks, What is the best way for them to meet and how should we go about preventing any nasty-ness from our dog. Would meeting out garden, off lead with a hosepipe at the ready be the best option?

As I say with any other breed we have met, small or big, all he wants to do is play, so any advice would be gratefully accepted.

Thanks in advance

Rebecca