Based on today's exchange rate of $1 US = ₤0.6342, you are looking at a price range of roughly $1600 to $3950. I've not heard the Wilson Benesch Arc, but in the US they are more expensive than that price range.
I recommend a number of different speakers made by
Salk Signature Sound. These are US made speakers, but Salk does ship overseas.
SongTower (floor standing)
Ellis 1801 TL (floor standing)
HT-1 (stand mount)
HT-1 TL (floor standing)
HT2-TL (floor standing)
The last speaker is somewhat higher priced than your upper range.
Reviews available online:
SongTower - Enjoythemusic.com
SongTower - Audioholics
HT1-TL - Enjoythemusic.com
HT2-TL - Audioholics
And is there a limit on the refinement and detail you can attain in the midrange with a 2way standmount since it has no dedicated midrange drive unit?
The presence or absence of a midrange driver, in general, has little to with sound quality. There are good and bad examples of 2-way and 3-way speakers. Far more important is how well a speaker's crossover handles the frequencies shared by different drivers within a speaker.