I believe there might be a rule that applies above a certain number but it happened to a friend of mine a few years ago. Basically a few people in fixed income sales at her bank got sent home at once - she apparently got an heads up from her manager the day before and that was it. The day it happened she went in in the morning, called into a meeting and basically offered the relevant notice(s) + statutory pay + an additional amount to leave without any fuss... and that was it, sent home with a decent-ish pay off. (While I'm sure there was more official detail to it, a token offer to find another role within the organisation or whatever other measures they need to take in order to be compliant I'm pretty sure they can, if they want to, simply pay people to go home and not come back in...).
edit - I believe it is greater than 20 employees when they have to give advanced warning/have a consultation period.