Played the whole album last night. Agree on the lack of top. Switched in and turned my treble knob full boost or full cut and made no difference.
I don't though recall noticing this back in 1977 when as new it was played again and again, guess I was just happy to hear Nic.
Here he is more recently, still that voice.
(Link thanks to Fretboard Journal. Nic Jones article in recent edition.)