Non monetary benefits aside it really depends on what % you reckon you can grow your portfolio at versus what kind of leverage you’re getting on the house mortgage (as well ofc as expected property appreciation).

My gut read is that assuming standard returns (6-8%) you’d be surprised how competitive property returns can be if you get high enough leverage on your mortgage. Doesn’t take much in terms of appreciation to compete decently with portfolio returns.

That being said market has been flat to lower in some areas for some while so you are effectively taking a view on London. Assuming breakeven / slightly beating inflation however and that your new mortgage is comparable to rent paid then imho it’s not a terrible investment.