Coming on ... now we've got

A - All Around My Hat
B - Byker Hill
C - The Cuckoo
D - Drink Old England Dry
E - Early One Morning
F - Four Drunken Maidens
G - Great Silkie of Sule Skerry
H - ??
I - Irish Rover
J - ??
K - ??
L - Lyke Wake Dirge
M - Maids When You're Young
N - ??
O - Oats and Beans and Barley
P - Prickly Bush
Q - The Quaker's Wife
R - Rosin The Beau
S - Skye Boat Song
T - Twa Corbies
U - Ups and Downs (Aylesbury Girl)
V - ??
W - Worried Man Blues
X - XXIV Tailors (Four and Twenty Tailors)
Y - Ye Banks and Braes
Z - Zulu Warrior (not in DT)

H is staring you in the face. For N, i was going to add that the serious allergy's him (though I left it out because it might have distracted you from other associations).

;-)
Ian