With all due respect bringing back the O-level is just a sticking plaster,pull in the votes,tinkering with the system kind of suggestion that ultimately cannot fix the education system..Only a complete overhaul will do that after a long,hard and considered consultation(cross party) which ultimately would be considered to be far too expensive to even contemplate.
Doesn't matter which government is in control they all come up with ways that are designed to gain politically without actually really making state education any better.