This could turn out to be interesting, I never really explored the c-decay theory
Albrecht, A. and Magueijo, J., Time varying speed of light as a solution to cosmological puzzles, Physical Review D (Particles, Fields, Gravitation, and Cosmology) 59(4):043516-1—043516-13, 1999
Clayton, M. and Moffat, J., Dynamical mechanism for varying light velocity as a solution to cosmological problems, Physics Letters B460(3—4):263—270, 1999
Adams, S., The Speed of Light, New Scientist
173(2326): Inside Science, p. 4, 19 January
2002.
Are these peer-reviewed journals ? They all propose a faster speed of light in the past.