After completing their acclaimed folk rock trilogy in 1979, jethro tull returned a year later with 'a', an album that introduced a different sound and a new line up.    tracklisting  1 crossfire                       2 fylingdale flyer                        3 working john, working joe                 4 black sunday                5 protect and survive                 6 batteries, not included                        7 uniform                        8 4.w.d. Low ratio                   9 the pine marten's jig              10 and further on                        11 crossfire extended version              1 working john, working joe take 4              13 cheerio early version                        14 coruisk                         15 slipstream intro