Here’s a fairly in-depth analysis of the mutations seen in the new variant: https://virological.org/t/preliminary-genomic-characterisation-of-an-emergent-sars-cov-2-lineage-in-the-uk-defined-by-a-novel-set-of-spike-mutations/563
Link provided by 2aProtects was the answer to my question. As I expected they have found the disabling mutation in the stop protein. Changes and deletions in the spike protein optimize interaction with ACE2 receptor and diminish immune system response.
Freegards to you both!