it makes c. £11k pa from an investment of £150k with no risk to the capital.
? No risk to the capital? Why?
If you want zero risk to your capital, open a saving account. The low return you get is the price you pay for the certainty of having zero risk to your capital. Anything else has an element of risk.
No one has a crystal ball. It may turn out to be a lousy investment or a great one – no one can really know. Most people who bought properties 10 years ago or so have made a killing, but over the last few years the stock market hasn’t done badly, either, and there certainly are some equity funds which have outperformed many properties. I’m not saying you should invest in shares, just highlighting that property is not necessarily a slam dunk. One could easily argue that both properties and shares are overpriced, but then what do you do with your money?
The rental yield seems very high but I’ll go with your numbers. 2 rooms at £8k, so I’d guess you could rent out the whole flat for £12k; 12/150 = 8% gross rental yield; I don’t know the area but it does look high.
As others have pointed out, are you sure you have considered all the costs? Taxes will probably be minimal, but how about the maintenance of the property, the cost of an accountant if your son doesn’t want to/can’t file his tax return by himself, etc.?
Let me come up with some semi-random numbers just to give an idea. Let’s say you buy the property for £150k but spend another £10k between stamp duty (£500), legal fees, some furniture, some minor works in the property. Your real investment is then £160k, not £150k. You rent the two rooms for £8k, but let’s say you incur costs of at least £1k per year (it’s a flat, so there will be ground rent, a management charge, the cost of servicing the boiler, etc): £7k per year. To be on the safe side, I’d say £6k to account for vacant periods (e.g. they give you notice before the summer and you only find a new tenant in September). You save £5k that you’d otherwise pay in rent. So this £160k investment makes you £11k (6+5), i.e. 6.875%.
6.9% is definitely not a bad return. However, it’s not set in stone; it could be considerably higher (no vacant periods and the property appreciates) or it could be significantly lower: if your tenants don’t pay the rent, what are your chances of recovering the money from students with presumably no assets and no income? If the property depreciates and you struggle to sell it or sell it for less than 150?
I’m not saying don’t do it – I’m just saying be aware of the risks.