The byelection result in Chesham and Amersham will encourage calls either for a 'progressive alliance' or for some less ambitious pact between Labour/Liberal Democrats/Greens. The likely result of the Batley and Spen byelection (a Conservative win, no doubt aided by the resurrection of the ghastly apparition of George Galloway, a singularly repulsive figure who, nevertheless, seems to exert a strange facination for many) will further increase speculation.
Although I would support such a pact (notwithstanding all the practical local difficulties), even if it were successful, it would not usher in democratic socialism. It would herald the demise of Pfeffelism, but in alliance with a party (the LibDems) many of whose members have individualist, 'free-market' instincts. There needs to be a common platform on which all three parties can agree, encompassing far-reaching political, economic and social change, which could appeal to voters who support Brexit.
As a matter of historical interest, in the past, when the constituency included Rickmansworth, the seat was adorned by the presence of the writer and historian Sir Ian Gilmour as its representative in Parliament , who was a genuine intellectual. The Social Democratic Party thought at one time that he would defect from the Conservatives. He was a friend of Roy Jenkins, and the most leftwing member of Thatcher's cabinet (until he was sacked in 1981).