Singapore had a completed naval base and useful coastal defenses, while the troops and aircraft assigned to Singapore and Malaya remained elsewhere or were diverted. The air-defense system also needed properly operated radar, earlier Hurricane deployment, and effective fighter coordination across Singapore and wider Malaya. Those measures could have produced a credible regional defense before the Japanese offensive. The whole land-and-air network determined the bastion's vulnerability; the orientation of its fortress guns explains only part of the problem.
Chapter · 8:12-11:03
Singapore defenses and the Malayan air shortfall
A completed naval base could still be vulnerable when troops, aircraft, radar, and fighter control were inadequate.