Questions from a pub neophyte

The entire pub experience remains a bit of a mystery to me so I’m allowed to ask #1: re The Lamb in Lamb’s Conduit Street (and any other pubs this applies to).

1. Snob screens: why?

2: Little two-inch-high nautical-style brass rails round the small tables: why?

Snob screens are basically like a massive opaque glass and wood barrier on the bar between the pint-puller and the punter, in which little doors can be opened so a face sees a face, and then shut again when disgust sets in.