post) suggested one further author who can be compared in some respects, although by no means all, to Poul Anderson. Fred Hoyle was a British scientist who wrote some Wellsian hard sf, mainly in collaboration with his son, Geoffrey Hoyle. Fred Hoyle's output was, of course, much smaller than Anderson's and he never invoked FTL, not even with a scientific rationale. Alien intelligences affected Earth in other ways. For example, an intelligent gas cloud entered the Solar System and, in a later novel, another star with its planetary attendants passed through.
Hoyle Senior wrote a stage play called Rockets In Ursa Major. I knew someone who had seen it performed. Both Hoyles novelized the play, near future sf assuming regular interplanetary spaceflight. They then wrote a sequel, Into Deepest Space, in which the familiar characters embark on an STL relativistic time dilation intergalactic journey like the one in Tau Zero. Instead of surviving into the next cyclical universe, they pass through (something like) a black hole-white hole system into our flip side universe. (I am relying on memory for this summary.)
Hoyle continues the British Wellsian tradition. CS Lewis wrote anti-Wellsian and anti-Stapledonian sf. James Blish wrote Wellsian sf but also post-Lewisian fantasy and sf. Philip Pullman has written anti-Lewisian fantasy. Hoyle was definitely pro-Wellsian philosophically although he did not explicitly refer to Lewis. Poul Anderson, unlike Hoyle, had a sympathetic understanding of religious belief.