I tried an alternative approach and listed the holes at each course by length and then repeated this exercise. Very briefly, the two shared the par 3s (Goswicks 2nd beat Silloth's 16th, Silloth's 12th beat Goswick's 9th) and Goswick was two up on the par 5s (Silloth's 13th beat Goswick's 17th but, in order, Goswick's 11th, 4th and 6th beat Silloth's 14, 17 and 5). I had S9vsG15 as a half, for anyone interested.
The match was won, however, on the par 4s, with wins for S3vsG7, S1vsG3, S7vsG5, S11vsG10 and S18vsG16. Goswick had wins at G1vsS8 and G8vsS15 but that means Silloth was 3 up on the par 4s and took the match 1 up.
I took lengths from the white tees. It's interesting how this exercise makes some of the better holes compete (S9vsG15, S2vsG12, S4vsG14, S7vsG5). I had three of those halved, with Silloth's 7th just winning against Goswick's 5th.