Here is the pattern.
I jotted this down from memory, if incorrect let me know so I can correct any errors.
The white should be done in garter stitch, and the red in stocking stitch. The row count, number of stitches, shaping etc is based on the original pattern so this jumper will be same size on your bunting.
I carried the red behind the white in the centre as only 3 sts wide, but used new strands for the cuffs, and a new strand of red after I got to other side 9sts of the white neck on row 26.
There were a lot of ends to weave in I’m afraid!

In white cast on 17 sts
Rows 1-3: Knit all stitches in white
Row 4: K 7 in red, K 3 in white, k 7 in red
Row 5: P 7 in red, K 3 in white, P 7 in red
Row 6: as row 4
Row 7: as row 5
Row 8: as row 4
Row 9: as row 5
Row 10: as row 4
Row 11:(belt, stocking stitch 3 rows) in black P all sts
Row 12: in black K all sts
Row 13: as row 11
Row 14: as row 4
Row 15: as row 5
Row 16: as row 4
Row 17: as row 5
Row 18: as row 4
Row 19 cast on 4 sts at beginning of row then P 11 in red, K 3 in white, P 7 in red
Row 20 cast on 4 sts at beginning of row then K 11 in red, K 3 in white, K 11 in red.
Row 21: cast on 1 st in red, change to white and cast on 3 sts, then k 3 in white, P 12 in red, K 3 in white, P 11 in red
Row 22: cast on 1 st in red, add white and cast on 3 sts, then K 3 in white, K 12 in red, K 3 in white, k 12 in red, K 3 in white
Row 23: K 3 in white, P 12 in red, K 3 in white, P 12 in red, K 3 in white
Row 24: K 3 in white, K 12 in red, K 3 in white, K 12 in red, K 3 in white
Row 25: as row 23
Row 26: K 3 white, K 9 red, K 9 white, K 9 red, K 3 white
Row 27: K 3 white, P 9 red, K 9 white, P 9 red, K 3 white
Row 28: as row 26
Row 29: K 3 white, P 9 red, K 1 white then cast off 7 sts (leaving 1 st in white each side of neck) P 9 red, K 3 white
Row 30: K 3 white, K 9 red, K 1 white, cast on 7 sts in white, K 1 white, K 9 red, K 3 white
Row 31: as row 27
Row 32: as row 26
Row 33: as row 27
Row 34: K 3 white, K to last 3 sts in red, K 3 white
Row 35: K 3 white, P to last 3 sts in red, K 3 in white
Row 36: as row 34
Row 37: cast off 3 sts in white then cast off 1 st in red, P to last 3 sts, K 3 white
Row 38: cast off 3 sts in white then cast off 1 st in red, K to end in red.
Row 39 Cast off 4 sts at beginning of row
Row 40 Cast off 4 sts at beginning of row
Rows 41-45 Do 5 rows stocking stitch in red
Rows 46-48 Do 3 rows stocking stitch in black (if you want belt on reverse)
Rows 49-55 Do 7 rows stocking stitch in red
Rows 56-58 Do 3 rows garter stitch in white
Cast off

Stitch on a buckle, sew up and smile