In this answer, I would stick to a 50-50 split and so you can spend 85 words more on less on 2 reasons why you want to become a lawyer at the firm, and then 2 key skills that you have and you could bring as a lawyer, like attention to detail and teamwork. You then link them to an experience where you showed these skills.
I know it might be hard, but succinctness is a skill that law firm looks for so it is important to practice this. I did apply to
Taylor Wessing last year and I got through the application stage and I used the tip I gave you and it worked well for me!
Good luck with the application and I hope I have been of some help!!