The land was requisitioned by Acts Of Parliament. A Parliament that was elected by a a tiny proportion of the country, and in no way reflective of Democracy as we recognise it now. The idea that compulsory purchase of land for national infrastructure projects is either new or somehow breaks ”hundreds of years of democracy“ is counter-factual.Landowners were compensated for the land that was requisitioned. The canals and railways were all private enterprises and used significant amounts of shareholder capital to buy land. I commend Christian Wolmar’s book Fire and Steam for a clear explanation of how the railways were funded.
If you want an example of government sequestering property, the nationalising of the railways is a good one. The shareholders in the railway companies were not compensated at all for the physical assets that were nationalised.
It couldn’t happen today; property rights are now enshrined in human rights law. The only recourse is compulsory purchase.
Buy Fire and Steam: A New History of the Railways in Britain By Christian Wolmar. Available in used condition with free delivery in Australia. ISBN: 9781843546290. ISBN-10: 1843546299www.worldofbooks.com
During the railway building boom, landowners were compensated, and the more powerful and influential they were, the better they were compensated.