Hi Larry,
Roasting in England? Must be around Hillsborough where it is in the mid 70F (24+C) otherwise England is in the mid to high 60s F into the 50sF!!
Do not want to recommend any alien species though you know that Boston Fern can handle it!! But here is a link to one native species that just might do ok in the sun if it received some misting during the mid day. Otherwise I would stick to Osmunda regalis (even though I have one of these in shade) as being the most tolerant of sun as a native species.
Check out this site BPS

Here is a link that might be useful: Hard Shield Fern

Hi Jerry,i'll check out those links.cheers.
As for climate,well i'm on the other side of the country to Hillsborough which is in Liverpool. I'm in county durham,north east. And tho weatheer sites may give those figures i can tell you than when the sun comes out it gets hot! A lot hotter than 60F!

Of the US native ferns, Thelypteris kunthii is the one I have that can handle sun. It is regularly recommended by a southern gardening magazine just for that reason.

Many species in the Cheilanthes genus are sun tollerant. You can also grow Platycerium veitchii in the sun. I grow veitchii in Houston where it's hot as blazes in full sun till about 2PM.
Platycerium veitchii
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Psilotun nudum, a fern family.
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And the ultimate sun fern Sadleria :) Good luck

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Some really neat ferns there Pat! That Psilotum is a fern? Looks like a succulent,like a Crassula!
Neat Platy there,very cool! And that last one,growing there on bare rock,reminded me of a tropical palm on a beach! Amazing stuff!
Jerry,i have no idea of The humidity here or how to measure it!

Larry,
Check the link below for weather in your area. You will see a map with city names. to get humidity etc click on the name of the city for a new window with humidity etc readings.
The Psilotum is not a fern but a fern-ally.
While it can endure direct sun it is really at home in shaded spots which are also coolish but not cold and lots of humidity!!

Here is a link that might be useful: Weather North East England

Well Jerry i checked for Newcastle which s the nearest to me and it says 72% humidity! That seems high!

Here is a link that might be useful: Newcastle's Weather

Psilotum or "wisk ferns" aren't really ferns they're fern allies. At least I'm pretty sure that's what that is. When some plants grow in the sun they get stunted etc. There's lots of xerophytic ferns that might grow in sunny England.