Below is an updated graphic of the known tracks made by Ocean Shield while towing the TPL.
The latest AIS data is that on the Green track commencing at 10/0822 UTC. At that time the vessel was heading 283°T at 3.0 KTS, and it is assumed that the towing depth has been reduced and she is about to slow and line up for the 293°T track. Towing at 2.0 knots would place her about a mile from the next marked position (15:44) at 15:00. The 15:44 and 16:19 positions are basically the same.
HMS Echo is operating to the East.
EDIT:: The latest graphic shows the Ocean Shield moving on 322°T track, possibly retrieving the TPL. The "stop" between 15:44 and 16:19 could have been to allow the TPL to maximize its depth. The "stop" is highlighted with the Yellow arrow. Ocean Shield heads away to the NW and picks up speed.
At 04:13 HMS Echo is now located near 21°S 104°E. The area of interest is probably very close to her position.