Happy New ...Rear bumper mount!

So, the rear bumper mount has now gone from this:

to this:

Pretty happy with my welding and it has ground down nicely (still requires a little bit of fine finishing). All is good ...or is it? You see, I made a rookie mistake along the way and I am now unsure if it is going to come back to bite me. Lets put the order of events into sequence and I shall explain...

After a lot of measuring (hours) I started cutting out the old bad steel progressively. I was continuously holding the new panel in place to ensure that I wasn't cutting too far back.
More hours of fitting and finessing later I had the panel 'dry fitted' and held in place with intergrips and c-clamps: 

The edges around the section to be welded were meticulously cleaned with the drill mounted wire brush to ensure a solid weld free of contaminates. I then started to tack the panel on, adjusting the profile and gently massaging everything into line where required:

Built up my tacks until I had a solid welded area, except for the rear section which needed cutting back further to remove mangled steel. I will eventually fabricate a suitable infill piece (see first pic above for the initial signs of that):

Good penetration on the rear side. I have now found the sweet spot within the settings of my welder for butt welding these thin body panels:

I ground the welds back and was feeling pretty good! 

I then thought I would chuck the old rear wing on to assess the fit and marvel at my handiwork. This is when I realised the error of my ways - I should have done this before commencing the welding! Basically, the two captive nuts on the repair panel did not line up well with the wing - although the edge profile did flow nicely (something at least!). It appears to me that the repair panel is possibly sitting a fraction too low. However, I am not sure I trust that old wing as it could have been knocked out of shape from the rear end shunt the car is know to have had. Plus, in general the wing was looking pretty forlorn, so I really need to repeat the fitment test with a decent wing before I jumped to a firm conclusion.

I will leave this section as it is for now and revisit at a later date - possibly with a reciprocating saw and a diction of crass expletives!