Sky's live pictures are obviously live, raw and therefore we fully expected to be a little disappointed.

Delightfully, we were wrong - even though lessons are still being learned, the clarity of the pictures is phenomenal. If anything the impact of moving from HD to Ultra HD is even more staggering than the transition from SD to HD, it's that good.

A great example was handily provided by the sprinkler system in the pre-match sunshine; the hazy partial rainbow that appeared on the UHD screen was nowhere to be seen in HD. It would be wrong to suggest that 4K pictures are just like being sat there, but at times it is easy to kid yourself you are looking through a window.

Ultra HD is stunning to watch - bringing clarity and colour accuracy
Ultra HD is stunning to watch - bringing clarity and colour accuracy

Every crowd shot, even from a distance, does not seem to diminish the details of people's faces, with sometimes amusing consequences you can lip read what the fans behind the managers are saying. You can see every nervous tic and irritated glance coming from the dugout, and these are just the incidentals to what is going on on the pitch.

Given the limited number of cameras (to put it in context the four UHD rigs and the supplementary 1080p camera being upscaled fall some way short of the incredible 24 cameras that were pitchside at Anfield the day afterwards for Liverpool v Manchester United) Jermaine Pennant's late winner from a free-kick, did not have enough angles to do it full justice, but the wide shot was perfect to see just how much quality it took to bend the ball past the wall.

Essentially, the Ultra HD seemed to allow the director to tell more of the story. By necessity and choice a lot less tight shots of players from the shoulders up were shown, but the replacements gave you more of the context of the player without losing the effect of seeing their face.

The Sony 85-inch television
The Sony 85-inch television

There are still issues that Sky (and the whole industry) needs to work through; the 50 frames per second that the company feels is appropriate for live sport is short of what the film industry has suggested, just one of several standards based discussions that need to happen and the broadcast quality kit is rarer than hen's teeth. In fact Sony have lent Sky huge amounts of the kit necessary to do these trials - including the four 4K cameras used at Upton Park.

In terms of what we saw, dealing with shadows on the pitch caused issues - although even the 90 minutes of test saw vast improvements, and finding the right focus was occasionally problematic.

Chris Johns, Sky's Chief Engineer and a man overseeing the test with all the pride of a new father, explained to us that Sky's enthusiasm for the product was huge but that the nascent Ultra HD market simply needs to catch up before any broadcaster on the planet can consider launching a 4K channel.

Which given TechRadar's experience is a real shame, because the lack of 4K content is going to be a key factor in holding up the television sales that will fuel the move to mainstream.

And this is just for backup
And this is just for backup

But most of all, it's a shame that the mass market is not getting the chance to see just how powerful 4K Ultra HD pictures are compared to what they are used to.

Even with bigger screens you can sit much closer because of the greater pixel density so you can be even more drawn into the action, the level of detail brings the picture to life in a way that's difficult to do justice to and the sharpness of the colours make the whole thing a pleasure to behold.

Sky simply cannot put a timescale on when we will see a Sky Ultra HD channel, there are too many factors outside of its control, but the excitement from the broadcaster at the prospect of 4K pictures is infectious.

The upshot of the demo is that Sky, and therefore other broadcasters worldwide are already capable of making first class live 4K content. And that should make us all more confident that Ultra HD is arriving fast.