They made it through to the last eight thanks to a last-ditch win against Stamford.
With each club playing one rink at home and one away, simultaneously, the result couldn’t have been any closer, with an extra end having to be played to decide the victors.
As in previous rounds, Louth’s away rink of Rob Lamb, Dave Warren, Keith Kelly and Mally Hewson came up with a win, this time by 19 shots to 13.
But the home quartet of Colin Smith, John Welsh, Mike Leverton and Mark Fremantle lost by the same score.
The one extra end was played at Louth and proved a very tense and fitting climax, with the hosts nicking it right at the end.
The next opponents will be County Durham club Stanley, but because of the distance between the clubs reaching this stage of the competition, matches are played at a neutral venue.
In this instance the tie will be staged at York Indoor Bowls Club on Tuesday, March 3.
* Louth’s mixed B team had a County League match when they entertained Skegness A.
They put up a creditable fight before eventually losing on aggregate shots by 99 to 93.
At the midway point, the four rinks were level, but as two of the Louth rinks began to pick up shots, the other two began losing them.
In the end Louth did manage two rink wins, with Michael Cheese’s rink taking their match by eight shots, but the best margin came from the rink of Ken Hasnip, Irene Bailey, Keith Dennett and Rita Jackson which won 28-13.
* At club level, APS kept their three-point advantage at the top of the Evening Fours with a 20-14 win against Wayouts.
Second-placed Fast Shippers enjoyed an easy win against Stags, but Alford lost ground when beaten 19-12 by Questors.
Barrie Robinson and John Welsh maintained their perfect record in the three-bowl pairs with a comfortable victory over Tina Reeson and Mike Norton.
The win kept them four points clear of nearest challengers Terry Cornwall and Simon Reeson.