An Anglo-Saxon Riddle

A young man made for the corner where he knew she was standing;

this strapping churl had walked some way--with his own hands he whipped up her dress,

and under her girdle (as she stood there) thrust something stiff, worked his will; they both shook.

This fellow quickened:

one moment he was forceful, a first-rate servant,

so strenuous that the next he was knocked up, quite blown by his exertion.

Beneath the girdle a thing began to grow

that upstanding men often think of, tenderly, and acquire.

Go on then - what do you think it is?