Acol:

This is a difficult hand for Acol unless the partnership has a shape showin

g relay.

A fourth suit forcing shape showing relay could work.

N.     E.      S.      W

         -        1    -

1   -        2    -

3   -        3    -

4N.    -        5    -

5    -        5N.    -

6    -        -        -

where:

3 - 4th suit forcing shape asking relay

3 - 5431. ( If South had 5 they would bid 3, 5422 - 3N, 5413 - 3 etc)

4N - Roman key card 

5 - 1 or 4

5 - ask for Q or K

5N - no Q 1K

After South reverses Noth plans to go to game so uses 4th suit forcing to check South’s shape. After South shows 3 support North can see with an adjusted 7 loser hand the possibility of a slam if South is maximum for their reverse.

However, thinking about it even with the probable common Acol auction on the day of :

N        E        S       W

           -         1    -

1     -         2    -

4     -           ?

It is surprising more South's did not bid on as North's 4 bid will surely be on the basis of a 7+ card suit and provided there is only 1 loser in the suit South should have been able to count 5 winner's and a ruff in their own hand to get to 12 probable tricks. Certainly enough to have then made a Roman key card enquiry to check if North held a  key card.   

Precision:

I'm not a precision expert and there are so many variations but this could be one possible approach. In some ways, Precision's ability to provide tighter point count information could count against it but pairs are more likely to have shape showing relays although perhaps not for a negative response auction.

N        E        S       W

           -        1     -

1     -        1     -

1     -         2    -

4     -          ?

where:

1 - 16+HCP any shape

1 - <= 7 HCP any shape

1 - 19 HCP any shape

1 - <=4 HCP any shape

2 -  5+ unbalanced

4 -  to play 7+

Whilst South can again count a probable 12 tricks if there is only one  loser, similar to the second Acol auction,  the more precise knowledge of North's HCP range might have put South off bidding higher. If the partnership had a shape showing replay after a double weak response then bidding could proceed more slowly.

Quite possibly, instead of leaping directly to 4 North may have invited with a 3 bid in which case South simply raising to 4 would close down the auction.

Imperspicuity:

The bidding would go:

N      E      S       W

         -       1    -

1   -       1N      -

2N     -       3    -

3    -       3    -

3N      -      4    -

4     -      4    -

4     -      6    -

-          -

where:

1 -  <= 6 Losers (L) 0-37 HCP any shape

1 -  <= 8 L 5+ 

1N  -   Shape asking relay

2N  - 7

3 - Shape asking relay

3 - 73 9 total losers

3 - Shape asking relay

3N  - 7321

4 - Loser asking relay

4 - 8 L

4 - CROSS

4 - 1 or 4 key card

6 - to play

An advantage for this type of hand of using losers for initial hand evaluation is that South, after using the rule of 18, is looking for slam after North's positive 1 response once a fit has already been found, so even if East made a 2 overcall it is likely slam will be biddable.

Utilizing an early shape asking relay allows South to have almost complete knowledge of North's hand shape and relevant keycards below game before making the final decision to bid slam. 

Again South can count 12 probably tricks provided there is only 1 loser, either ruffing a , or setting up a long  for the 12th trick.

For us, our modified form of Acol might get us there:

S. 2C (19+ HCP or no more than four Losers) - forcing for one round, but not necessarily GF.

N. 3S - 6+ Spades.

S. 4NT - RKC (14/30).

N. 5C - one KC.

S. 6S - with fingers crossed.

Not at all scientific (we are Intermediates), but it is actually possible with our agreement.

Not saying it would have happened at the table, though!