Calling all armchair generals! Boudica's Last Stand.

[Renatus]

It seems more and more obvious that even with a huge body of tribes people mustering on their doorstep, the inhabitants of Colchester didn't feel under any threat at all until the very last minute when they retreated to the Temple.

Why would they be unconcerned? There must have been a reason for an officially recognised gathering.

It is clear that they were concerned at one time, otherwise they would not have called for help.  A message had to be sent to Decianus, he had to assemble his meagre force and that had to get to Colchester.  I have speculated that messages were sent out simultaneously to Decianus, Ceriialis and Suetonius but, in fact, Tacitus only refers to the one to Decianus.  If this means that this was the only message, then Decianus, on realising that he could not muster enough men, must have sent out the other messages.  After all, Cerialis must have been informed of the danger by someone.  This creates further scope for delay.  Tacitus states that the colonists did not erect defences or evacuate those who could not contribute to the defence of the colony because those sympathetic to the revolt interfered with their plans.  What were those plans?  Presumably, they concerned the preparation of defences and evacuation.  Tacitus implies that, but for that interference, they could have created some form of defence, so there must have been some time in which to do so.  What story the sympathisers with the revolt spun to the colonists must remain a matter for speculation but one may assume that it involved reassurance that what looked like an ominous gathering of tribespeople was actually nothing out of the ordinary and no cause for concern.