These are the rogues who, when not holding court in the Fianna Fail tent at the Galway Races, are depriving thousands of people of a home of their own by sitting on vast unused land banks.

But while Hobbs was returning to one of his favourite hobbyhorses, the mouthy Corkman may have overlooked a whole new class of villain in the nationwide battle for a place on the property ladder.

In a piece of research that looks at the trials and tribulations facing people trading up to bigger properties, Bank of Ireland has unearthed a startling statistic: one in three of them hangs on to the house they are leaving.

That adds up to a lot of starter homes that never find their way back on to the market when their owners decide to move on.

Small wonder that firsttime buyers are being squeezed ever more effectively out of the picture.

The reasons for stretching yourself to keep the house you are leaving are many. For starters, there is the usual emotional attachment to the first real home you call your own, even if it was a shoddily-built shoebox. If you play your cards right and are lucky enough to find good tenants, that shoebox can become a goldmine.

According to Bank of Ireland's numbers, turning your first home into the beginnings of a buy-to-let empire can be relatively pain-free. For example, only 3% of those trading up reported difficulties getting the mortgages they needed, even though so many of them are now borrowing for two houses. This means borrowing an average of 250,000 to buy the new house on top of the debt still owed on the first property.

If the thought of all that borrowing makes you queasy, try telling yourself that most of it is 'good' debt that has allowed you transform your first home from an expensive roof over your head into a lucrative asset, a vital building block in your financial future.

That's a compelling argument but, while it might stack up financially, it could also land you in hot water with the taxman. For starters, by holding on to your first home, you risk losing the special stamp duty entitlements for first-time buyers.

First-time buyers pay lower rates of stamp duty, and in many cases are completely exempt, as part of the government's effort to give them a leg up on to the property ladder.

The catch is that, if the house is rented out within five years of being bought, the taxman will seek to claw back the difference.

That's a hefty tax exposure . . . 13,750 on the average starter home costing 275,000 . . . and a lot of buy-to-let converts are not even aware of it.

And the tax headaches do not end there. One of the top attractions of investing in property is the ability to write off the interest bill on the mortgage against rental income for tax purposes.

By straddling two rungs on the property ladder, you will have no shortage of debt, some of it on the old house but probably most of it on your new home.

That's the worst debt structure from a tax point of view because only borrowings used to buy the investment property . . . in other words, the old house . . . qualify for the tax write-off.

You would have to question how many of the budding investors in the Bank of Ireland survey are aware that most of the extra debt they have taken on carries no tax advantages. It is a question that will also interest the Revenue should they decide to take a closer look at the buy-tolet boom.

Perhaps the only consolation is that having unresolved tax 'issues' need not block your entry to the Fianna Fail tent in Galway.