If you look at the Results thread as well as the discussion thread you will see others in a similar position.
It is highly likely that 219 will be enough for STRS - it has been in recent years. STRS do not give rankings, only scores. From their website (I am sure you have seen this already but maybe in the excitement it didn't sink in - I do understand that feeling):
How are places allocated?
Whether your son will be allocated a place at Sir Thomas Rich’s school will depend upon:
How many pupils have scored a higher standardised mark for our school than your child
How many of those children have stated a preference for our school, and
How many of those children have stated a higher preference for another school and whether
they have met the criteria for a place at that school.
Sir Thomas Rich’s will offer places to the highest scoring children until we reach our admission number of 108. We are likely to have more pupils who pass the test than can be offered a place.
They can never be sure as it is not predictable how many whose children passed for other schools will choose STRS ahead of them. The admissions team try to make a pass mean a place, and managed it the year before last, but not last year.
HTH and well done to your son.