Police are not exempt from speed laws.
"By virtue of Section 87 Road Traffic Regulation Act 1984 (as amended by Section 19 Road Safety Act 2006),
(1) No statutory provision imposing a speed limit on motor vehicles shall apply to any vehicle on an occasion when–
(a) it is being used for fire and rescue authority purposes or for or in connection with the exercise of any function of a relevant authority as defined in section 6 of the Fire (Scotland) Act 2005, for Ambulance purposes or for Police or Serious Organised Crime Agency purposes,(b) it is being used for other prescribed purposes in such circumstances as may be prescribed, or
(c) it is being used for training persons to drive vehicles for use for any of the purposes mentioned in paragraph (a) or (b) above, if the observance of that provision would be likely to hinder the use of the vehicle for the purpose for which it was being used on that occasion."
It seems to me totally reasonable that the emergency services should be allowed to train under realistic conditions. This includes negotiating whatever numpties are using the roads at the time.