Oh dear, a goady thread, written by yet another person who feels they can have a valid opinion on teaching because they have been to school. I'm sorry but this does not make your opinion valid, and quite frankly it isn't.
Every teacher out there will have a degree, which although doesn't mean they are "clever" means that they have achieved something that a majority of the population has not. Actually only 34.4% of the working population (16-64) has a degree or equivilent qualification. So teachers will have evidence that they are more qualified, and by imp;ication able to prove that they are more intelligent than the majority of the population. So to answer your question, yes all secondary school teacher are clever, they can prove it. Also for the last 5 years a basic entry requirement has been a 2:1 from a university, meaning that more recently qualified teachers can prove it even further!
So is having "top grades" a requirement, no, because teachers have already proved that they are in the minority in the country in achieving a high educational standard.
In further counter to your flawed argument ( classic argument from fallacy) there are the many points made on here about non subject expert teachers providing excellent levels of education. I would, if you will allow me, like to ellucidate my experience with reference to specifics.
I am a Russell Group qualified teacher with many years experience and several "outstanding" ratings by OFSTED under my belt, the most recent being during a 2013 inspection. This last rating was very pleasing because, dear heart, it was a lesson delivered in a subject I have not studied since I was in the 3rd year of secondary school!
How was it then that a teacher without even an O level or GCSE was able to deliver such a good lesson? Well it would be because I am good at planning lessons, thinking of activities that facilitate learning, I'm clever and can read up on my subject to a sufficient depth that I can answer almost all questions, and I can communicate what I want, and what outcomes I want to the students clearly. All of this makes a successful lesson.
The group that I took for that lesson achieved excellent results, and make no bones about it for a mixed ability group (A-G) in a non-selective comp, 76% A to C is extremely good. To drill down on the data further 85% of those students achieved their target grade or higher. Again following lessons planned and delivered by someone without a direct qualification in that subject.
Here's where my experience gets better, I then took over the operation of this qualifications A Level, and with my first cohort of year 13's through this year (again in a non-selective comp) we recieved an ALPS level 2, which means we are in the top 10% of schools in the country for this subject. Planned and delivered by a non expert.
Many, many subjects are delivered to excellent standards in schools by non expert teachers who may not have been the best students at high school.
Ridiculous posts like yours, and many others on here, the constant judging, critiquing by the general population who feel they can because they went to school, is one oif the reasons that "good" people are leaving in droves.
Now tell me, should posters have to fully work out their arguments so that they don't ge ttheir arse handed to them in public like you just have?