So the kite was ordered on Monday 31st March, first class, and has yet to arrive. I have opened a dispute but nothing can be done until next Thursday due to Royal Mail's lost post policies.
I bought the kite from this seller
and the feedback on the page is reasonably good. However, a quick google and it turns out they also have an online shop separate from ebay and after a bit more googling they don't seem to be the best of people to buy from. The reviews of the website say a lot of items never arrive, as per my case. They seem to let the customer know that the item has been dispatched and then when it doesn't arrive, claim that it was never in stock in the first place.
Anyway, I just thought I'd let you know. Hopefully it will all get sorted, my kite arrive and and can leave good feedback for them.
I'm not overly concerned as I know I'm covered by ebay & paypal, but it's hassle I could do without.