PEARSON Test Score confusion...

Please can anyone guide me regarding the PTE Academic test score on the UKBA guidelines below.

UKBA requirement - B2 level
Students must achieve a minimum PTE Academic score of 51 across all four skills of listening, speaking, reading and writing.

My brother received his result yesterday and his OVERALL score is 56. He needs to take admission in University and he need at least B2.

I am just wondering as although his overall score is 56 but one of his skill level have score of 48 only. Do UKBA requirement 'across all four skills' mean overall score?? or each of skills must have at least 51 score??

It needs to be a minimum of 51 for each of the 4 parts. The uni may object and not issue the CAS anyway.