Police have revealed that Diane Tytheridge, who has been missing from her home in Bicker since Wednesday, spoke to a bus driver before she disappeared.
A force spokesman said the last sighting is now at 8.38am on the Wednesday, at Boston bus station, where she made enquiries to the driver about buses to Skegness.
It is unclear whether she actually caught a bus or not.
The spokesman said Diane was wearing blue skinny jeans, a white t-shirt under a black fleece jacket, and she was carrying a blue crescent-shaped holdall. She was wearing her hair in a pony tail.
Police are continuing their appeal for Diane or anyone who has seen her to get in touch.
Inspector Dan Whyment said: “Diane has been missing for almost a week now and her family are distraught. We are urging anyone who has seen Diane, or who has any information that might help, to contact us.
“We are also appealing directly to Diane to let someone know she is safe.”
Police have said that if Diane does not want to let anyone know where she is the charity Missing People offers a number of ways that those who have left home, for whatever reason, can confidentially make contact to let somebody know they have not come to harm.
The charity can be contacted by calling or texting 116 000 or emailing firstname.lastname@example.org
The police number is 101 and the incident number is 371 of June 25, 2014.