Eliza McCarthy's maternal and paternal lines can be traced to early/mid 19th century East London in the neighbourhoods of Spitalfields, Christchurch, Shoreditch and Bethnal Green during an era when British and European immigrants were arriving and settling in the borough of Tower Hamlets. The name McCarthy is of Irish descent, originally from MacCarthach.  Broken down,  Mac means Son of, and Carthach means Loving. (McLovin?).  The timing corresponds with Ireland's 1845 potato famine when a million Irish emigrated to live in Britain or America.  But now:

The Irish are the lost wave of immigrants in Spitalfields because they left the least trace. If you walk around Spitalfields, you can see some of the houses where the wealthy Huguenots lived and you can go to the synagogue that’s still there in Sandys Row, and you can visit the Bengali curry houses. But there’s almost nothing to remind you of the Irish except for the sign-writing on Donovan’s paper bag shop in Crispin Street.

 

https://spitalfieldslife.com/2015/07/04/dont-do-it-magazine/

Eliza's travel log from her 1949 trip to England.

London's population jumped from 1 million to 6 million citizens during the 100 year span of 1800 - 1900, the East End being a catch-all for many working class immigrants, and making a name for itself in the Weaving Factories, Garden Markets and industrial development.  Queen Victoria and Prince Albert supported advances towards research in agriculture and newly emerging sciences such as the novel Applied Chemistry.  This was lucky for chemist William Perkin who accidently discovered the colour mauve in its synthetic form while trying to find an accessible cure for malaria by forming a synthetic quinine molecule from coal tar byproduct.  Once patented, mauve was first used commercially in 1857 by silk dyer Thomas Keith in his Bethnal Green operations. At present the synthetic colours that have been developed based upon Perkin's process are synonymous with the food and clothing industries, they are also indispensable in medical practices for locating cancerous cells and colouring plated samples of various diseases - parabolically linking to Perkin's original medical intent (Mauve, Simon Garfield, 2000).  Perkin's discovery was made in 1856 in the attic of his father's house on King David Lane in Upper Shadwell - a few blocks away from where Eliza's mother Caroline possibly lived on John Street in 1871.

Map of 1882 WhiteChapel neighbourhood with landmarks.  Click on the map to view in a separate window

Source:  1882 Reynolds Map of East London Source Birkbeck History Dept.   (https://commons.wikimedia.org/wiki/File:1882_Reynolds_Map.jpg)

Alternately the sensational downsides to a population boom within city restrictions are a more popular topic.  Websites are dedicated to how rough this over-crowded borough was, plagued by poverty and disease and violence forcing desperate acts - the backdrop to many Dickens' novels; he used to walk in this district and take notes.  In 1884 John Merrick (the elephant man) was put on display for the first time on Whitechapel Road in a store across from the London Hospital.  When Eliza wrote  'Wilks St.' as her father's address, it was a Wilkes street William McCarthy lived on 15 years before Jack the Ripper terrorized the neighbourhood - the same part of London in which one "Mad Jimmy" Kray, grew up and laid forth the stomping grounds for his grandsons, the infamous Kray Twins in the 1950's.  https://www.findmypast.co.uk/blog/discoveries/the-kray-family

Spitalfieldslife.com is one website worth a visit because the articles bring together all walks of life in East London from the mundane to scandalous.  An apt starting point is the photograph collection from John Thompson's street life.  The photos were first published in 1876 - a few years before Eliza McCarthy was born, and so the imagery is an intimate route to Eliza and her family's life before they came to Canada in 1885.  https://spitalfieldslife.com/2011/03/28/john-thomsons-street-life-in-london/

Another site to visit is the Explore Georeferenced Maps.  Here, the National Library of Scotland has developed an interactive map that overlays old maps over modern geography as addresses are typed into the search bar.

Click on the image of the London City Center Map and the Explore Georeferenced Map will open in a separate window.  It is set to London 1893 - 1895 for finding the addresses listed below.