[cryoshon]

general source to understand the phenomenon in prior variants: https://www.frontiersin.org/articles/10.3389/fimmu.2021.7571...

mutation profile of this particular variant: https://assets.publishing.service.gov.uk/government/uploads/...

summary of the phenomenon in layman's terms: when binding at 100% efficiency, antibodies bind to portions of the spike protein like a key fits into a lock, so it's easy to "unlock" the lock, thereby neutralizing the viral particle. when there are mutations which affect the shapes of the different portions of the spike protein, it's like the pins in the lock shifting so that the key you used before might not work without quite a bit of jiggling, assuming you can get it to unlock the lock at all. the more mutations that increase the amount of jiggling it takes, the more the pins in the lock become intractable with the key you have.

this set of analogies is imperfect in a few ways, but hopefully it helps you to understand the gist of the problem.