He ordered the pretended harper to be sent into his tent, that he might hear him play and sing.

Alfred went, and thus he had the opportunity of completing his observations in the tent, and in the presence of the Danish king.
Alfred found that the Danish camp was in a very unguarded and careless condition.

The name of the commander, or king, was Guthrum.[1] Alfred, while playing in his presence, studied his character, and it is (not) improbable that the very extraordinary course which he afterward pursued in respect to Guthrum may have been caused, in a great degree, by the opportunity he now enjoyed of domestic access to him and of obtaining a near and intimate view of his social and personal character.

Guthrum treated the supposed harper with great kindness.

He was much pleased both with his singing and his songs, being attracted, too, probably, in some degree, by a certain mysterious interest which the humble stranger must have inspired; for Alfred possessed personal and intellectual traits of character which could not but have given to his conversation and his manners a certain charm, notwithstanding all his efforts to disguise or conceal them.
However this may be, Guthrum gave Alfred a very friendly reception, and the hour of social intercourse and enjoyment which the general and the ballad-singer spent together was only a precursor of the more solid and honest friendship which afterward subsisted between them as allied sovereigns.
Alfred had one person with him, whom he had brought from Ethelney--a sort of attendant--to help him carry his harp, and to be a companion for him on the way.