The big picture is the collapse of the old parties, Conservatives and Labour, along with the "centre" of British politics. Voters in both parties, appalled by the dismal efforts to provide a better economic future, have abandoned the mainstream parties, and are seeking change that will improve their lives.
Reform promises to make Britain Great again by stopping immigration, reducing taxes, reducing public services, and hoping that will result in the growth of jobs and opportunities. They propose to cut workers' rights and protections, and make Britain a place where billionaires and multinationals will want to invest in.
Greens promise to make Britain Great again by taxing billionaires and multinational companies, and investing in the economy to create jobs, housing and opportunities for the ordinary people.
The economic arguments for both approaches are debatable. Each has positives and negatives. So it comes down to an emotional, rather than an intellectual decision. What sort of country do you want for you and your children?
A country built for the benefit of the super rich, with ever increasing levels of obscene wealth and obscene poverty dividing the country? Or a country built for the benefit of it's citizens, with ever increasing levels of equality and social justice uniting the country?
So the importance of Gorton and Denton, to answer the original poster, is that it's the first insight into which way the voters of this country might lean. Which has been obscured by smoke about the particulars of whether Labour may or may not have won if, but, blah, blah blah....
The old centre parties that have held British politics in a stranglehold for a century are dying, and a new politics is being born. In front of our eyes. Reform and the Greens may be irrelevant in ten or twenty years; everything is changing so fast. Whether it's the Brave New World, or the last nail in the coffin, is a purely personal political viewpoint.