Applied online via a basic form involving your personal details and background, as well as a few longer questions where you were asked to provide some examples regarding particular competencies.
After passing this stage I was an invited to an assessement centre in London in October 2017. The assessment centre was well-organised and wasn't overly difficult and if you do your research you are not taken by surprise. There is a 1 on 1 interview with questions primarily involving the key competencies which can be found online. There was then a group assessment excercise whereby we had to decide on the suitability of two different extra-curricular programs for a school before we were then asked to deliver a one minute presentation on a particular element of this. Then you had to deliver a pre-prepared 7 minute lesson. For the lesson, be calm and engaging, and ensure that if the assessors (acting like schoolchildren) ask questions/express confusion then you deal directly with them.