Irish Foreign Birth Registration FBR processing time

My FBR application of 18 July 2016 was processed in 120 days.

I applied for Irish Citizenship through Foreign Birth Registration (FBR) using the London Embassy.

18 Jul 2016 - Application sent to the London Embassy.
10 Nov 2016 - Application approved and FBR certificate dated.
15 Nov 2016 - Certificate posted back to me.
16 Nov 2016 - Certificate received.

There was no acknowledgement of receipt other than my proof of outbound delivery.
The embassy website says applications can take 6 months.
I didn't contact the embassy to ask about progress as I didn't want to add to their workload.
My application took around 120 days / 4 months.
If application volumes were increasing following BREXIT then factor in some additional time.

Thank you to the staff at the Irish Embassy in London.