"From 1909 onwards the island also became used as one of the Admiralty’s first high powered shore wireless telegraphy stations [...] Four wooden aerial ‘Marconi’ masts in eight foot tabernacles were erected, each standing 150 foot tall and held fast with wire stays." - https://maritimearchaeologytrust.org/wp-content/uploads/2020...
So I think what must have happened is that the initial 150-foot wooden masts (1909) were replaced with steel masts at some point before 1917, and the first quote above confused the two stages.
Ok, yes, found some supporting text.
"The new station at Horsea consisted of 4 wooden aerial masts of overall height 150 feet with 8 'spreader' masts of 60 feet surrounding them. [...] The first station was out of date within 6 years and plans were made for 4 masts of an overall height of 446 feet. The first went up in 1913 to be followed by two more in 1914, the last was not finally
being erected until 1921." - https://historicengland.org.uk/research/results/reports/7019...
For completeness, in this blog post we're back to wood again: "The masts dominated the skyline and were constructed as a triangular wooden lattice 7 feet each side. [...] By 1933 wireless technology no longer depended on the wooden masts and they were replaced by steel towers of 180 and 100 feet in height." - https://manorcourtupdate.blogspot.com/2015_08_01_archive.htm... but I'm inclined to go with the primary source (the Daily Sketch page).
Annoyingly, primary sources are thin on the ground - I don't think the accident made it into the papers at the time.
Drifting off the topic of the mast itself, I found that Knoulton died in 1981, and a subtly different account of the rescue: "on 14th September 1917, on Hornsea island a seaplane collided with a Poulsen mast and remained wedged in it; the pilot was unconscious and had been thrown out of his seat on to one of the wings. [Deck Hand ABBOTT Ordinary Seaman KNOWLTON and Seaman RATH], at once climbed up the mast for 100 feet, when one of them [?RATH], making use of the boatswain's chair, was hoisted up by men at the foot of the mast to the place, over 300 feet from the ground, where the seaplane was fixed. He then climbed out onto the plane and held the pilot until the arrival of ABBOTT and KNOWLTON. A gantline was then secured round the pilot who was safely lowered to the ground. All three men were well aware of the damaged and insecure condition of the mast, which was bent to an angle where the seaplane had become wedged. One of the three supports of the mast was fractured, and so far as the men knew, the mast or seaplane might at any time have collapsed." - https://www.greatwarforum.org/topic/77065-dangerous-perch/
Abbott died 1977, and has a wikipedia page: https://en.wikipedia.org/wiki/George_Abbott_(GC) That's the most complete description of the rescue I can find, and is backed up by other sources. I haven't linked.
