If your engineering group already uses C# then it might not be such a difficult sell - the two languages are highly interoperable, so you may be able to carve out a particular greenfield project and write it in F# instead of C#. Note, though, that we've found it necessary on project `FooBar` to create specific `FooBar.CSharp` wrapper libraries that C# users can consume; this is because idiomatic API design looks pretty different between F# and C#.

(If you're interested in quant finance in London, I work at G-Research which uses F#; I write almost solely in F# there. You can contact me privately if you like at [email protected].)