The results from two large-scale fire tests on a hollowcore floor plate, supported on protected steelwork, are presented in this paper. The two tests were identical except for the connection details between the units and supporting steel beams, with Test 2 having a more robust detail to tie the units and beam together. The floor was purposely subjected to a very severe fire created by specifying unrealistically small ventilation openings, compared to modern office construction. The hollowcore floor plate performed very well supporting the full applied static load for the duration of the tests. A beneficial load path mechanism created by lateral thermal restraint to the floor units was highlighted, which has not previously been considered. The tests showed that the small-scale standard fire tests, used to assess fire resistance periods, can be very unrealistic and ignores the beneficial effects of whole building behaviour. The test results presented reinforce the experience gained from real fires that hollowcore floor slabs have good overall inherent fire resistance.