Dot's parents were Jack and Vi Todd, who married as fighting began marking the beginning of the Great War. Vi's mother, Ivy Makepiece, had been abusive and bitter towards her children, but Vi did not want to make the same mistake with her three kids - Dot and her older siblings Jim and Sally - although she still kept a firm hand. Dot and Sally loved their mother and relied on her to sort out problems, such as when Dot fell in love with a Frenchman named Jean, blissfully unaware that he had also taken up a sexual relationship with Sally. When the truth came out, an unaware Jean dropped by to see Dot, and Vi kneed him in the groin, telling him to never return.
Dot first met Elsie through Elsie's affair with Dot's brother Jim. She also met her eventual husband Walter Greenhalgh through Jim, as he visited the Todds one Christmas when Jim was denied leave. After Jim was killed, Vi suggested Dot agree to Walt's request for a date. When Dot said she could never want Walt and that Vi only wanted him around because Jim had died in his arms, Vi beat her and tore at her clothes and threw her out. Dot lived with Elsie for several months, but eventually made up with Vi. She also married Walt, although she was still not very fond of him and enjoyed spending time with other soldiers, including Gregg Flint, an American GI stationed at Burtonwood.
In 1945, Dot and Walt married and moved to 18 Victoria Street. After the war, Dot gave birth to her only child, Samantha, who died of TB aged 13 months. By 1960, Dot and Elsie worked at dress shop Miami Modes together. Dot continued to flirt with other men and was open to the occasional fling. When Gregg Flint returned to the country in 1967, Walt found out that Dot and Gregg were seeing each other and went to thump Gregg, but in a case of mistaken identity he hit Steve Tanner, Elsie's boyfriend. Gregg got the message anyway and was scared off.
Dot generally only visited Coronation Street to see Elsie, although she did know some of the other residents. In 1963, Dot thought she was up for a promotion at Miami, but Christine Hardman got the job. Dot was eventually given the supervisor's job in 1966, but she left the shop to work at McAverty's Department Store in 1968, where she ran the lingerie section.
By 1969, Dot was back at Miami and Walter had finished with her. Dot moved in with Elsie but when Elsie was caught with Dot's bag which contained stolen dresses, Dot let Elsie take the blame. Dot even admitted her guilt to Elsie, and begged her to keep her out of it. They both lost their jobs, and Dot never showed her face in Coronation Street again. In 1974, while talking over old times with Sheila Crossley, a friend of Elsie's, Emily Bishop remarked that Dot had vanished off the the face of the Earth.
- When Dot first appeared in Coronation Street, she was credited and referred to as Dorothy Lane. Later episodes credited the character as Dot or Dorothy Greenhalgh. Dot appeared irregularly from 1961 to 1969 and was one of the longest running recurring characters.
- Dot was the Judge of the Street's Boxing Day fancy dress party in 1966, crowning winners Jerry Booth and Annie Walker.
- Dot and Harry Hewitt are cousins; their mothers were sisters.