I agree it’s unlikely to happen (haven't heard anything about it for ages) and even if it does it’s going to be a very deep line so shouldn’t affect you.

I forgot to say any crossrail 2 project would have to tie into an upgrade of clapham junction rail station to accommodate the trains which ain’t happening anytime soon .

Project was put on hold back in March due to lack of funding and the TFL finance crisis . Even if it did get resurrected , it could take another 5-10yrs before construction even started and then another 5-7yrs of construction . So best case you can sleep easy for another 15 yrs+.

The safeguarded route was under Wandsworth common flowing under Bolingbroke pub and across hiller , montholme and gayville roads . But that safeguard was dropped as part the project suspension and the argument of whether Balham or tooting .

The council planning maps suggest it will go to Tooting so under Wandsworth Common and closer to the Toast Rack
 

We have seen some houses for sale on the following roads Gayville, Montholme etc..

When digging further in to it, cross rail 2 is proposed to run further up on the same road as one of the houses and underneath the other one.

Will this devalue the house? I don't have an issue with living near/over a line but I wouldn't want to be stuck with a house I was unable to sell.