| Heat Number - 1 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 3 | 1 | Stanley THURLOW | 12 | Lincoln Vulcans SC | 1:49.18 |
| 4 | 3 | Samuel NICHOLS | 12 | Grantham SC | 1:35.34 |
| 5 | 2 | Luca HALLAM | 12 | Grantham SC | 1:46.76 |
| Heat Number - 2 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 2 | 5 | Francesco MONACO | 12 | South Lincs Competitive SC | 1:34.32 |
| 3 | 7 | Lewis TOPHAM | 10 | Louth Dolphins SC | 1:28.33 |
| 4 | 9 | James CASH | 10 | Deepings SC | 1:27.08 |
| 5 | 8 | Adrian ELERTS | 10 | Grantham SC | 1:27.90 |
| 6 | 6 | Jacob TURNER | 10 | Boston Amateur SC | 1:30.20 |
| 7 | 4 | Fabian KOLASA | 11 | Grantham SC | 1:34.54 |
| Heat Number - 3 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 11 | James HUCKLE | 11 | Lincoln Vulcans SC | 1:25.66 |
| 2 | 13 | Jack HICKS | 09 | Lincoln Vulcans SC | 1:24.82 |
| 3 | 15 | Benjamin MORRIS | 09 | Boston Amateur SC | 1:23.91 |
| 4 | 17 | Charlie BISBY | 11 | South Lincs Competitive SC | 1:20.30 |
| 5 | 16 | Archie FRENCH | 09 | Lincoln Vulcans SC | 1:23.03 |
| 6 | 14 | Matthew TOMPKINSON | 09 | Louth Dolphins SC | 1:24.20 |
| 7 | 12 | Freddie TRAGNI | 09 | City of Linc Pentaqua SC | 1:25.33 |
| 8 | 10 | Rian SOUTHWOOD | 10 | Louth Dolphins SC | 1:26.65 |
| Heat Number - 4 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 19 | James THOMAS | 10 | Gainsborough Dolphins SC | 1:19.00 |
| 2 | 21 | Oliver SHEPHERD | 09 | Deepings SC | 1:17.53 |
| 3 | 23 | Benjamin DERBY | 08 | Lincoln Vulcans SC | 1:17.10 |
| 4 | 25 | Kieran NG | 10 | South Lincs Competitive SC | 1:16.10 |
| 5 | 24 | Zach HOPKINSON | 09 | Grantham SC | 1:16.17 |
| 6 | 22 | Oliver SEALEY | 08 | Louth Dolphins SC | 1:17.29 |
| 7 | 20 | Aaron SADLER | 10 | South Lincs Competitive SC | 1:17.67 |
| 8 | 18 | Jacob HEGG | 10 | Lincoln Vulcans SC | 1:20.12 |
| Heat Number - 5 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 27 | Hayden POTTS | 08 | Lincoln Vulcans SC | 1:15.62 |
| 2 | 29 | Matteo MONACO | 09 | South Lincs Competitive SC | 1:14.99 |
| 3 | 31 | Daniel HEPPLESTONE | 10 | Lincoln Vulcans SC | 1:13.02 |
| 4 | 33 | James NICHOLS | 09 | Grantham SC | 1:10.81 |
| 5 | 32 | Frank LAMB | 09 | South Lincs Competitive SC | 1:12.90 |
| 6 | 30 | Layton ANNISON-SNOWDEN | 09 | Louth Dolphins SC | 1:13.56 |
| 7 | 28 | Aidan FITZGIBBON | 08 | City of Linc Pentaqua SC | 1:15.48 |
| 8 | 26 | William TAYLOR | 08 | Louth Dolphins SC | 1:15.97 |
| Heat Number - 6 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 37 | Stefano FIORE | 07 | South Lincs Competitive SC | 1:09.24 |
| 2 | 43 | Leon BAILEY | 06 | Louth Dolphins SC | 1:07.31 |
| 3 | 49 | Thomas HEPPLESTONE | 06 | City of Linc Pentaqua SC | 1:03.80 |
| 4 | 55 | James DOBNEY | 04 | Grantham SC | 1:01.10 |
| 5 | 52 | Alex SADLER | 07 | South Lincs Competitive SC | 1:03.24 |
| 6 | 46 | Joshua CLARKE | 08 | Grantham SC | 1:04.44 |
| 7 | 40 | Jacob BRIERS | 08 | Deepings SC | 1:09.12 |
| 8 | 34 | Christian O'MALLEY | 06 | Lincoln Vulcans SC | 1:10.80 |
| Heat Number - 7 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 38 | Jake ADAMS | 07 | Louth Dolphins SC | 1:09.20 |
| 2 | 44 | Harry KINGSTON | 04 | City of Linc Pentaqua SC | 1:06.08 |
| 3 | 50 | Isaac BANHAM | 05 | Skegness ASC | 1:03.73 |
| 4 | 56 | Joseph PARNELL | 07 | City of Linc Pentaqua SC | 1:00.20 |
| 5 | 53 | Ewan COX | 08 | City of Linc Pentaqua SC | 1:01.97 |
| 6 | 47 | Owen HATHWAY | 06 | Grantham SC | 1:04.20 |
| 7 | 41 | Jacob SOWDEN | 06 | Lincoln Vulcans SC | 1:09.11 |
| 8 | 35 | Ben LORD | 05 | City of Linc Pentaqua SC | 1:10.53 |
| Heat Number - 8 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 39 | Jacob FISH | 09 | Grantham SC | 1:09.13 |
| 2 | 45 | Finnley DANBY | 06 | Boston Amateur SC | 1:05.06 |
| 3 | 51 | Alfie BISBY | 07 | South Lincs Competitive SC | 1:03.60 |
| 4 | 57 | Rico BRINGEMAN | 05 | South Lincs Competitive SC | 56.60 |
| 5 | 54 | Thomas BRUCE | 06 | South Lincs Competitive SC | 1:01.74 |
| 6 | 48 | Oscar GOLDSMITH | 08 | South Lincs Competitive SC | 1:04.01 |
| 7 | 42 | Ryan NORTON | 07 | Boston Amateur SC | 1:08.00 |
| 8 | 36 | Daniel DEGNAN | 08 | Grantham SC | 1:10.38 |