Thanks for the comments guys
I used an very old VGA Card & cut it down to size, The one side slots between the RF shield & the lowercase next to the mouse port.
The other side due to the slight angle on the Case's interor is fixed by leaving some sharp teeth on the bracket & this grips quite happily into the corner of the case. I'm surprised as to how solid & stable it is but it is holding well.
I didn't want to use Hot glue & felt the original plastic bracket would probably not be strong enough.
What I am looking into now is a better solid fixing of the LISA socket, If you do a soft drop 10mm of the A1200 the Indivision just pops off & I wouldn't want this too happen whilst powered up.
Occasional screen glitches are also cured by lightly tapping the top of the A1200 case, so something more permanent is needed.
BTW has anyone tried the latest 40.6 HighGFX Test.iff file yet ???