I few of us at a wargames club in Coventry (UK) started playing BASIC Impetus last week and loved it. Needless to say we are still getting our collective heads around the rules. One question we couldn't find the resolution to was:

Situation:
When a unit with an impetus bonus wins a melee is it blocked from pursuit of the retreating unit by a frontal overlap from another enemy unit that it was already in contact with?

This other enemy unit was not involved in the initial melee as it will be attacked by the next friendly unit in line once the initial combat is resolved.

Remembering that a Main melee unit cannot also offer support to other combats, does the winner of the melee:
A) Sit and do nothing, and play moves on...

B) do they move to side of enemy blocking unit, become parallel to retreating unit, and then pursue?

C) or Attack second enemy unit they were already in contact with as there pursuit action, even though there is no actual movement, and even though they will not have the normal main melee unit requirement of being the unit in contact with the enemy unit with the most overlap.

I hope that makes sense, and sorry if I have missed the answer in the rules or forum somewhere...

Just looked at the 'examples of multiple melee' on the site. Our situation looks like example 2. Imagine B has won the melee and 2 retreats, what happens to B's pursuit. Battle between A and 1 is yet to be resolved, what happens?

I think I follow what is happening - AFAIK the one that has just won the melee but is unable to pursue now counts as support for the next melee. In this way it is important which melee to do.

We are running a BI fun comp in June in very North London (takes me just over an hour to get to my daughter in Leamington) if you guys are interested

I confirm the answer given by Rich.

A Unit cannot be at the same time a Main Unit and a Supporting Unit, but in this case things are changed after the "first" melee and in the "second" melee it is now a supporting Unit. Note that in this case the now supporting unit has no impetus bonus because didn't move (follow up).

Thanks for the advice, very helpful.

Another question on pursuit:
If during pursuit you contact another enemy unit, but not the one that had just retreated, we have assumed this initiates a combat between these freshly contacted units immediately. Is this correct?

It does and you get your impetus bonus if fresh

Here's where I love the step up to full Impetus as you can have a unit on 'opportunity' charging into the pursuers which means you can set up 'traps' ala the Carthaginian 'fall back' to flank attack type thing