40 minutes ago, ApertureS said:

when did I mention slave cylinder seals being replaced with a fluid change?

You didn't, but since the fastest ways to the lowest points in a sealed system are through the seals at those points...

1 hour ago, ApertureS said:

Coupled with the fact that oil floats on water then the water if in high enough concentrations will sink to the lowest points which is the calipers - in theory

 

I can confirm from bitter experience that it does so when there is a contamination of water in the master cylinder, whether the tiny amount absorbed through hygroscopy comes out of solution and sinks I can't say, I doubt it though.

 

The Galaxy concerned was another of my write off rebuilds, a loom fire, I had wrongly deduced that the water ingress to the master cylinder reservoir was due to the Fire Brigade using a high pressure hose under the bonnet, the Ford recall revealed that water was draining from the scuttle directly onto the reservoir cap which had a very sloppy fit between the moving parts needed to allow removal of the cap without unplugging the sensor lead.