It clearly was, it says 30-50 metres was the norm for this TFR and by my reckoning, 30 metres is about 100ft. So why not 500ft?
I think my concerns were to do with the split second where a glitch or unrecognised obstacle, such as a tree in full summer plumage, might cause the TFR to malfunction and leave the pilot with a near impossible task to get the aircraft higher. I've no doubt the TFR was capable and for the greater part did what it was designed to do, but at extremely low level you'd have to be either possessed of nerves of steel, or a fatalism of zen proportions to allow it full control.
As an aside does anyone remember a UK based flying group that had some ex-RAF jets back in the 70's/80's, painted black ? Did they have a Bucc ? I have a vague memory of sitting in one at Mildenhall or Duxford. They did have a hunter and something with torpedo wing tanks (perhaps a Canadian something ??). What ever happened to Mike Beachey-Head's Buccs when his company was wound up ?