What is this tool / part?

[Helvetica]

Can someone help me identify this tool? It’s one of my sister-in-law’s, dad’s tool who has since passed away. Any help identifying it would be appreciated

 

[Sideways]

It doesn't look like a tool to me. It looks like it might be one of those specially shaped washers used on monoblock type kitchen taps to secure the tap into the worktop. Bolt(s) would go in the centre cutout or the two holes, the big gap is where the small bore flexible hoses come out of the base of the tap.

 

[marcros]

that was my first thought too.

 

[galleywood]

+1