After several emails and conversations with other professional birders, we have finally come to the conclusion that these Swans were in fact Whooper Swans! Even though the first picture didn't clearly give that away, This picture below showed just about enough information to work out that the parent birds had enough yellow down the beak to be Whoopers. You can clearly see that on the bottom right bird which was the bird leading the pack. This was likely a family of Whoopers as they do travel in families!
I'm so chuffed about this! Quite sad that they were put off from landing though... I'm in search for answers at the moment as to why there were so many Wind Surfers/boats on the water at this sensitive time of year. The SSSI failed to aid these birds and that isn't acceptable.