From 'It Crawled The South - An R.E.M. Companion' by Marcus Gray:

"In 1984, when faced with criticism that his guitar style was strongly reminiscent of the Byrds, Peter tended to respond by citing Big Star and the Soft Boys as his true influences. In early 1985, while in London having a not particularly pleasant time recording 'Fables Of The Reconstruction', Peter bumped into ex-Soft Boy Robyn Hitchcock, who invited him to guest at a Dingwalls performance of his new band the Egyptians on 15 March. "I played like eight songs out of 14, or something," says Peter."

The below setlist from The R.E.M. Timeline website contradicts how many songs Peter Buck guested on, but Peter is well known for exaggerating things like this!