This is where the main character and her friend are gathered waiting for Vincent Hemming to arrive to London. 

Regent Park is one of the several royal parks in London and is located in the inner part of the city between Westminster and the Borough of Camden. Mary mentions this park in chapter ten, as she is experiencing an emotialn dilemma with Mr. Jackson. 

In chapter 8, Mary pretends to sympathize about the ladies' expeditions to the London Music Hall. During this time, the music hall was a British theatrical entertainment that was very popular. It became the site of new-era music and entertainment, particularly focused on leisure activity for men to go and see the eloquant ballet dancers. 

https://en.wikipedia.org/wiki/Music_hall

This is the location of the St Mary's Church Conwy where Wordsworth was inspired to wrtie the poem "We are Seven"