Fastening a window blind onto a steel lintel

[ruud1boy]

I'm trying to fit a blind to the underside of a window aperture, drilling upwards into the wall to hang a blackout blind.
I've hit an immoveable object which, after a bit of headscratching, I'm guessing must be the steel lintel.

Is it feasible / sensible to try & hang the blind like this?

[thedoctor]

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