item 10 on page 23 of the KC rules and regulations for conducting spaniel trials says:

"It is a refinement if a dog indicates the presence of game before flushing the
game positively"

How can a spaniel indicate the presence of game? by pointing? by slowing down or by speeding-up? 

Depends on the dog.  Some might flash-point, just a brief second.  Some might become more intense and purposeful - an experienced handler can tell when a dog is onto game.

I thought they froze

I'd suggest it's by the dogs' action, if you have done anything like working trials, the dog does something called 'knocking' when it's caught the scent of an article.  In the same way, you should be able to read if a dog has picked up the scent or seen something it's working for.  The action of spaniels seems to be important in trials, and the judges must have some experience of how the dogs work, and be able to spot the body language of a dog working, and indicating when it's onto something. 

Is it a fault for a springer or cocker to hesitate or point befor go in for the flush on a trial?  

I've no idea, but I can ask for you, I know a few people who compete in spaniel field trials. 

I would be very much obliged to you! 

Not a problem, will ask the OH a bit later when he gets back in, he's out beating today. 

I'm guessing the answer will be dependent on an individual situation though, and whether the judge deems the dog to be too hesitant, or whether it's just a momentary pause or indication, as well as whether the dog seems to pause often etc.  It may also be partly down to the type of ground, cover and amount of game, as well as the weather.  Frosty cold weather is terrible for holding scent, and throws a lot of dogs, so combined with poor terrain it could possibly throw the normal working style of a dog or dogs??  Furrows and dips often hold scent in as well, and birds/animals are very good at tucking down into these, remaining as hidden as possible to the eyes and nose. 

Thank you.
And ask him as well  please what  is the ideal flush for a spaniel?

Just had a quick chat with him, and yes, it's down to the individual dog and handler, and what the judge reads of the dog's action, whether they believe the dog has identified the presence of game before it's flushed. 

As for the ideal flush, he said that the most important issue is that the dog is steady to flush.  On a training session I went along to, one of the spaniels sat even before the whistle was blown, they'd flushed a rabbit, and the second it had bolted the spaniel's bum went on the ground.  I'd suggest that's probably an ideal flush, is that the sort of answer you needed? 

Thank you very much!
Didn't he say if it was a fault for a springer or cocker to hesitate or point befor go in for the flush on a trial?  

No, it's not a fault, but, as I'd guessed, it's at the discretion of the judge; they decide whether the dog is hesitating, ie unsure, or indicating, ie sure, and that's down to reading action, or body language of the dog.  As I'd also guessed, there are a number of things on the day that may well affect how a dog works, and a normally confident dog may well lose confidence depending on the situation it's asked to work.  So you'd have to be sure whether the dog was actually hesitating, or had indicated that it was on to something.  But the main thing is the steadiness to flush, any indication is a bonus to that (apparently) but that steadiness is paramount.