Like a Welch mile, long and narrow. His story is like a Welch mile, long and tedious.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Welch Fiddle * Welch RabbitNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes