Rather surprised that no-one worked this out so I'll deconstruct it piece by piece.
A laid back well known battle spawned an upright messenger - though
not the later one from the same source.
The well known battle is the 1066 Battle of Hastings (a misnomer as the battle was 10km north of the town, so was the aircraft actually named after the town of Hastings?) so we get the Handley Page Hastings - laid back because of its tail wheel undercarriage.
The upright messenger is the Handley Page Hermes which was a development of the design. Hermes was the winged messenger of the gods - upright because of the nose wheel undercarriage.
The later one from the same source is the Handley Page Herald - one definition of a Herald being a messenger.
A regal representative became
enobled before taking flight
The regal representative was a Viceroy, thus we get to the Vickers Viceroy which, before its first flight was renamed the Viscount (Viscount being a rank of British nobility) due to the post of Viceroy being done away with on Indian independence.
and quickly extinguished the upright
messenger's grandfather's light
Apollo was the grandfather of Hermes. The Armstrong Whitworth Apollo was built to the same original Brabazon Committee spec as the Viscount but only two were built and the type was a failure.
though all were put in the shade by an
astronomical brilliance that all too soon crashed and burned.
The De Havilland Comet 1
I'm looking for 6 types from 4 manufacturers in a single country.
The country, of course, is England.
The upright messenger's grandfather's engine type was unsuccessful, but doubled up it gave power to a successful bird.
The Apollo was powered by the Armstrong Whitworth Mamba turboprop which did not come up to expectation. Doubled up to power contra rotating props, the Double Mamba succesfully powered the Fairey Gannet.
It sounds like the first two had engines from mythology
The Hastings and Hermes were powered by Bristol Hercules engines.
and a
development version of the "upright messenger", which didn't reach
production, had a more up to date power plant named after the founder of
an ancient city.
Two Hermes V aircraft were built for the Ministry of Supply in 1949 to be powered by Bristol Theseus turboprop then under development. Theseus, in mythology, was the founder king of Athens.
Two of the other types had engines which might indicate a sharp weapon
or equipment used in what some say is a sport but were actually named
after something completely different.
The two other types are the Viscount and the production version of the Herald, the HP7, both powered by RR Dart engines. The Dart was not named after the weapon but was one of the RR series of engines named after UK rivers, the River Dart being in Devon.
The last type sounds as if its power came from a supernatural source,
though in later marks it could be said that the power came from a
bardic related source!
The Comet 1 was powered by RR Ghost engines. Later versions were powered by RR Avon engines, Shakespeare is known as the Bard of Avon, the River Avon flowing through Stratford upon Avon.
That's it....simple really
6/10 to Milairjunkie for effort!