Grab - your post pretty much bears out what my guy tells me about Newtones, around £6-50 a set and sound great. He seems to think they last a little better than most other non-coated strings though - maybe his sweat's not so acid?
Cliff - I've always used Elixir 12s or the D'Addario EXP 12s on my Lowden O25 - they're both dear, the D'Add's sound better when new but don't last anywhere near as long as the Elixirs. I can get 4 to 6 weeks from a set of Elixirs compared with 2 weeks from the D'Add's. My only complaint with the Elixirs is that they seem to have a low tension and the low 'E' goes out badly when I capo up, but a little re-tune is a small price to pay for that long life!
I've also tried Dean Marley Alchemy's on both my Lowden and my Martin J40 but they sound very tinny and 'twangy', too much for my liking.