Thames Christian School vs Portland Place School

[HKtoUK]

We are looking to shift to UK and my older boy will be doing a school/igcse board shift after completing year 10. We have, after many tests and discussions, finally received 2 offers for him from 1) Thames Christian School at Battersea and 2) Portland Place School at Marylebone (Its next to impossible to get admission between year 10 and year 11 and can't risk going to state school as they can waitlist him in Sep20 thus wasting valuable time in this crucial year). We are confused as to which one is more academically advanced since he will only be there for a year for his GCSEs. Any views from parents welcome. Please help us decide! Thank you.

This is only from viewing them as someone with a child who has SEND, so may not be that relevant to you.
Portland Place is generally seen as the school you go to if you have no other place. However, we really liked it. It felt like a state school with monied kids and lots of funding for great opportunities. Thames Christian we liked more as the kids were much more down to earth and the intake is much more ethnically mixed. It is also a lot cheaper than PP. Thames Christian also has a number of kids with dyslexia etc and they give them tremendous support. All kids use laptops in lessons and the standard we found was higher than PP. We would've gone there if it wasn't so far from us.
You may also find a lot of people now moving their kids from private to state so there may be some places in more academic schools. However, both of these schools would be able to support your child really well imo. PP doesn't deserve it's rep in terms of academics.

Thank you so much @Malmontar. Its helpful.