Dave,

From the timeline and location of enlistment I imagine your grandfather enlisted in 1914 in the Regular Army, the LF's home being Wellington Barracks, Bury. The Pals Battalions were raised later in the war when it was realised the men wouldn't be Home before the Leaves Fall. They were usually raised as additional battalions of extant regular formations but numbered after the recruiting figures were in.

This was the "Your Country Needs You" recruiting campaign (Kitchener's Men). That provided the British Army with forces to fight at Loos (1915) and The Somme (1916).

Conscription followed (1917.)

AndyG