My guess is the difficulty to date has been with the targeting system. I saw the laser itself (obviously a low power version, and probably a much earlier technology) being used to hit metal plates in the lab at a UK Uni in 1986 (work sponsored, I believe, by MoD). Quite alarming at first as you didn't know what to expect. RSRE then took over the work until its staff were made redundant about 10 years ago (when MoD pulled QQ's funding). Which makes Min(DP)'s statement a little misleading. I'm sure the RAF would like to get back into the game!