Tell him it's time to do a remod and as a business you hope to market the place at a substantial increase.

Don’t have the time to do property management right now however as I have a full time W2 (accredited investor) and a family to raise. 

My mum currently lives there, she is 80 and not very well, but you would also become a tenant in common and as such if you had the time you could profit 100% from the transaction, as I need cash urgently and am willing to heavily discount the asset.I am wondering if there is a market out there where someone wants to get a foothold in the London market by buying my part of the property.

It sounds like you've absorbed a bunch of problems already and a new sewer line and the current basement situation will cost you way less than the $50K in fees to sell it. 

Also, if the LazyDog exits at some point, and a new tenant needs to come in - who will bear the architectural/remodelling expenses?

$6k tax.Ins,hoa, not to mention utilities . took out a HELOC off of our personal home ( res.worth $900k, and a 260sq ft studio, mtr. $1450 mo.) for$ 220,000 for the deposit.

Along with a kiddy-pool sized litterbox in one corner of a room, cat urine and feces in the OTHER corner of the room on the carpet (newly installed by the seller when I bought), and a smell that made my eyes water walking in the front door.The lease has a clause for Tenant-Caused Damages resulting from tenant negligence.

Her credit isn't the greatest, but she's super sweet and a hard worker, so you are certain it will work out.

There’s a ton of investment pouring in, job growth, and a growing demand for housing.

I live in California (Central Coast) and have built a 12-door portfolio in Detroit, which has been a great market for both cash flow and long-term potential.Detroit still offers properties well below the $150k mark, with strong rent-to-price ratios and a market that’s seeing growth in key areas.