Advice on Schooling Please

Hello

Here is the breakdown:
Primary education
Primary education lasts six years divided into two cycles: lower primary (Standards I- III) and upper primary (Standards IV-VI). All children must attend primary school from the age of 5. At the end of Standard VI, pupils sit the Certificate of Primary Education (CPE) examination. This examination serves the dual purposes of certification and eligibility for admission to secondary school.

Secondary education
( usually at age 12)
Secondary education is divided into two cycles. The first cycle, of five years' duration, is divided into two stages: students in Forms I-III follow a more or less common general course; Forms IV and V prepare students for the Cambridge School Certificate or the General Certificate of Education, Ordinary level (O-level) and cover both core subjects and a wide range of options. The second two-year cycle prepares students for the Higher School Certificate or the General Certificate of Education, A-level.
Up to Form III, students follow a broad-based curriculum. Options are available as from Form IV. All schools do not offer the same options. Streams offered are general, vocational, scientific, commercial and technical.

You may get a better idea by comparing with their programme:
https://www.westcoast-schools.com/programme.html
and the FAQ:
https://www.westcoast-schools.com/faq.html

See whether you can use the argument of him attending an IEB school to "defeat " their resistance  and  for comparison with their bragging rights on their site .

Also check when the academic year starts : usually in January  and if your brother wants to join in September that may be the reason they want him in Form III until exams for the year 2018.

Disclosure: I am not familiar with those new private schools which have mushroomed over the years .

The public education sector has changed since last year last year, I don't quite remember the new system but I think there is a grading system and an examination called PSAC that has replaced the CPE.