Wiring help, bathroom light and fan (1)

[brotchaq]

Hello all
Long time reader, first time in a while poster.

I am looking to add some smart elements to my domestic lighting. First task is to understand how things are wired. I have posted an image showing the wiring in loft and at switch and am hoping that I could get confirmation of my assumptions.

I think that:
loft wire 1 - switch wire c
loft wire 2 - switch wire a, b or indeed neither
loft wire 3 - switch wire d

Thoughts?
Thanks in advance

 

[brotchaq]

All

Another question if I may.

In the attached image, can someone explain why the V variable output terminal of the Danlers dimmer is connected to the adjoining fan switch common, rather than the L terminal on the dimmer switch?
Is this OK?

Thanks in advance

 

[EFLImpudence]

In the attached image, can someone explain why the V variable output terminal of the Danlers

It doesn't matter; it is alternating current.
Not sure if it makes a difference with two-way switching.
Swap the wires if you want to.

dimmer is connected to the adjoining fan switch common, rather than the L terminal on the dimmer switch?
Is this OK?

Yes, that also doesn't matter - for one way switches.
All a switch does is connect the two wires together.

 

[EFLImpudence]

I think that:
loft wire 1 - switch wire c
loft wire 3 - switch wire d

Yes,

loft wire 2 - switch wire a, b or indeed neither

As you say, although neither a nor b is actually necessary for operating the switches, so

I would think a or b is a supply and b or a supplies something else; can't tell which is which.

 

[SUNRAY]

The whole thing is a bit unusual, I'm guessing the fan may have been a later addition.