Everyone tells me renting is throwing money away — my spreadsheet says otherwise, so where am I wrong? Ran The Numbers

Check what you are actually doing with the difference, because this is where these models usually fail in practice rather than on paper. Renting and investing £450 a month beats buying in a lot of scenarios. Renting and spending £450 a month does not. If the difference is genuinely going into an invested account by standing order rather than into your current account, your model is honest.

The line most people leave out of the model is that not all of the mortgage payment is a cost. The interest, the service charge, the ground rent, the insurance and the maintenance are money gone; the capital repayment is a transfer from one of your pockets to another. So the honest comparison is rent versus the non-capital portion of ownership, plus the opportunity cost of the deposit. Rebuild your sheet that way and see whether the answer survives — for a lot of people it still does, especially with a service charge in the picture.

The two-year relocation risk is doing more work in your favour than any of the arithmetic. Round-trip transaction costs on a UK purchase — stamp duty where it applies, legals, survey, agent fees on the way out — commonly land somewhere in the region of five to eight percent of the price once you add both ends. If you might move in two years, you need meaningful price growth just to break even on the friction. That is not an argument against buying, it is an argument against buying now.

Politely disagreeing with the framing rather than the numbers. The spreadsheet is right and it is also not the whole decision. What ownership bought me was that nobody can give me two months' notice, and I stopped treating my home as provisional. That has a value which is not zero and which I could not have put in a cell before I felt it. Whether it is worth £450 a month to you is a question the sheet cannot answer.

One line that is missing from most of these sheets: the maintenance reserve. On a flat you have a service charge, but you also own everything inside the front door, and boilers, floors and windows do not care about your model. I use one percent of the property value a year as a placeholder and it has been roughly right over eleven years — some years zero, one year enormous.

Terse: with a possible relocation inside two years and a service charge that size, the sheet is not wrong. Revisit it when the job is settled, and get someone qualified to look at your numbers before you commit either way.