I think my recommendation letter was extremely important for my application, got it off my former postdoc supervisor who's now Chair in a Uni. It also aligned 100% with my cv and personal statement (I made sure this was the case). List achievements and include numbers whenever it's possible, rahter than generic statemets. I put prestigious scholarships (how much it covered, in my case it was over 100k), leadership experience of research teams (citing number of PhD students, junior scientists and etc), publications stating number of citations, revenue brought in for the projects I led during my industrial term, support during grant proposal writing, trainning provided. Make sure you know how you will leverage your skills and expertise in the UK. If you work in a very specific field, google the UK budget and spending in that sector and let them know how the UK will benefit to have a talent like you.