Gbp/usd - 1.6120...Sterling experienced a roller-coaster ride y'day as price rose to 1.6436 in European opening only to collapse to 1.6082 later in the day on rumours (later denied) that PM Brown had resigned. Order book is relatively thin ahead of U.K. PPI data (08:30GMT) n U.S. non-farm payrolls (12:30GMT). Stops are noted at 1.6080 with buying interest fm Middle East names reported at 1.6050. Fresh offers are lined up at 1.6180 n 1.6210/20...