You're right in your concerns regarding that this resembles the " Serif 'J' " fake as it is in fact the actual ORIGINAL design the bogus shield was based on, the unknowm maker type 4.5. Besides differences in the font and basic design compared to the fake, the example you show is correct in being made from magnetic steel, as the fakes are always made in zinc. This is a very nice example of an original shield, no problems, but you were wise to question it before considering purchasing it.
For reference here's a fake example in zinc.
'I do not think we can hope for any better thing now.
We shall stick it out to the end, but we are getting weaker of course, and the end cannot be far.
It seems a pity, but I do not think I can write more. R. SCOTT.
Last Entry - For God's sake look after our people.'
In memory of Capt. Robert Falcon Scott, Edward Wilson, Henry Bowers, Lawrence Oates and Edgar Evans. South Pole Expedition, 30th March 1912.
Thank you very much Ned. I will be adding this shield to my collection confidently now!
looked ok to me too.