You'd be surprised how many clubs play a good standard without covers. As I said, it's rare in the TVL as most clubs have enclosed grounds but the only one that use to stand out was Kew, who are based on common land. Windsor are in a similar situation which is why I wondered if they had covers. Div 2a is a pretty decent level which makes it more interesting if they don't.
In the Wetherby League a number of Div 1 clubs do not have covers. Though it's supposed to be a village league the top clubs certainly do play a good standard. My club has basic covers and sightscreens, as we feel both are a requirement to play a better standard of cricket but alot of clubs in yorks don't.