Re drills for technique - there are a couple of stretches here that will help.
The last stretch is esp good as it shows what should be happening with upper body. Important to stretch through the lats (ie the torso) rather than just trying to reach forward with the arm. Makes it easier to get the hand and arm in the right position. Doing that stretch before a length and then focusing on continuing that stretch while swimming the length is a good way to getting good form.
He was interviewed in the belief that he had highly sensitive or stolen information. He stayed with a known film maker who was working on this issue, and is the boyfrind of the guardian reporter, he admitted carrying journalistic materials, and so there was more than reasonable suspicion that would allow him to have been arrested under the Official Secrets Act or some other legislation.
Fair play to the security servcies
except that if you do hold someone for any time you should be very sure what legislation you do it under. You cant just hold someone and then pick and choose your grounds after. It was anti-terror legislation they used.