The award is recognition of his contributions to mankind through his insight into the origins of mass and also through establishing astroparticle physics as a new branch of physics.Kibble died on the 2nd June 2016 and he cannot retire the prize, but in every case we can remember his most important contribution, Global Conservation Laws and Massless Particles with Gerald Guralnik and Carl Richard Hagen about the Brout-Englert-Higgs mechanism:
An intersting reading about the story behind the paper is The History of the Theory of the Spontaneous Breaking by Guralnik:
Shortly thereafter, as we were literally placing the manuscript in the envelope to be sent to PRL, Kibble came into the office bearing two papers by Higgs and the one by Englert and Brout. These had just arrived in the then very slow and unreliable (because of strikes and the peculiarities of Imperial College) mail. We were very surprised and even amazed. We had no idea that there was any competing interest in the problem, particularly outside of the United States. Hagen and I quickly glanced at these papers and thought that, while they aimed at the same point, they did not form a serious chall enge to our work.
G. S. Guralnik, C. R. Hagen, T. W. B. Kibble, 1964, 'Global Conservation Laws and Massless Particles', Physical Review Letters, vol. 13, no. 20, pp. 585-587 http://dx.doi.org/10.1103/physrevlett.13.585 (sci-hib)