Reg, G4FGQ wrote:
"Perhaps somebody might be prepared to state the power actually radiated
from feedlines in watts."

Someone has. A feedline is a way to get energy from here to there.
Usually we want to keep all the energy on or close to the line as it
travels and lose as little as possible to radiation and conversion to
heat.

Terman gives an approximate formula credited to Sterba and Feldman for
radiation from a 2-wire nonresonant line, provided that the lengrh is at
least 20X the spacing and the spacing is less than 0.1 wavelength:

Radiated power/Isquared=160(pi D/lambda)squared.

D/lambda is the spacing in wavelengths

I is the rms line current.

Terman notes that the parallel line radiates 4X the power that a doublet
of length equal to the line spacing would, providing that the line and
doublet currents are equal.

Terman provides a figure to be used to adjust the estimated radiation
upwards for longer feedlines (up to 5 wavelengths), and for greater
heights (up to 0.5 wavelength above the earth).

See 1943 "Radio Engineers` Handbook", page 194.

Best regards, Richard Harrison, KB5WZI