Sorry if I am confusing the reading of these graphs here!

If you assume the uv scale starts at zero , then the first green band covers zero to 1.0, second green band 1.0 to 2.0 and so on.

i.e all the uv numbers are rounded up, does this not make sense?

I think you are right as UV indexes can be inbetween for example 1.3C or 4.6, and that if it reaches the top of the defra number then it is indeed that number. 

Also those talking about the met office forecast I've  come to suspect these are rounded to the nearest whole, and also only represent the top likely index for that day based on whichever run they are derived from. The past 2 days down here in Portsmouth have also had 7's in the forecast but in reality the highest recorded at at a local private station was 6.3. 

Also defra have more detailed graphs available but apparently only for certain stations and upon request that give indications of how accurate the automated graph are as human input is put to use 

The (simple) way to look at it is that "Protection Needed" starts at UV3 from a WHO perspective so the yellow is from 3.0 - 3.99, and therefore the scale starts at 1.0, or that's how I always read it. Not sure why Reading don't give the readings over to the ECMWF HQ which is down the road from the Uni...

That's a very good point tdf, and one I'd overlooked. Of course, health is the key reason UV data is included in forecasts. Your point reaffirms what I have explained.

Chilton 6.7 yesterday, but only 2.9 today.

Last 2 days: Camborne- 6.8, 7.1; Chilton- 6.8, 7.0.

So a 7 in inland S Britain.

Reading is back on and backdated to the cut-off date. Highlights:

10/4/19: 4.2

18/4/19: 4.8

21/4/19: 5.0

30/4/19: 5.9

12/5/19:6.5 (5 days 12th to 16th inc. >factor 6).

21/5/19: 6.7

7.6 in Camborne, 7.3 in Chilton and- guess what. Having cheered Reading's return from the flatline, it's turned off today. Churlish.

Chilton top of the pile with 7.6. Ahead of Camborne.

Chineham (GW) 7.1

Reading 7.8

Chilton 8.5

Camborne 9.0

Fantastic!

Reading 7.8

I can certainly believe that - out with the wolves yesterday and we all said the sun felt fiery, far stronger than it had of late.

The MetO forecast for yesterday had 5 as the forecast value, but it also had cloud all day... although there was cloud, it was mostly cumulus and the sun shone for most of the time.

Last two days:

Reading 7.5  6.5

Chilton 6.9   7.3

Impressively, this morning Reading made 6.0 at about 11am before apparently clouding over; and Chilton was 8.1 shortly after 12. 

Update: sun returned in Reading- reached 8.1 (highest for some time); Chilton recorded its first 9 of the season. That's got to be worthy of note- we're >3 weeks from the solar zenith still.

Chilton 8.0 today; Camborne 5.6

Excellent contrast that Chilton only managed 1.7 today but that is equivalent to the best sunny days in early February- Chilton no doubt suffering from the deluge/ overcast skies; and yet there was still UV available at 1.7; June!

UV 8s forecast widely in the SW as far N as mid-Wales today. More 8s hinted at despite the humidity in places on Wed or Thurs, this time further east.

Reading has had 4 x 7+ this month so far, peaking yesterday at 7.9 when Chilton reached 8.3.

Reading 7.8

Chilton 8.1

Reading 8.0; Chilton 8.3

Reading 8.2

Chilton 8.4