There was a time when it seemed as if first-time buyers would be kept off the property ladder forever.

Mortgages became almost impossible without a deposit put down by mum and dad and vast areas of the country became unaffordable for the first-time buyer on an average salary.

How things have changed. After four years of decline, the number of first-time buyers has grown for two years in a row, and last year the growth, at 22%, was the biggest in a decade. Not only that, 45% of the purchases financed by a mortgage in 2013 were made by first-time buyers.

For young people who want to buy a house this is obviously good news. Indeed, with prices remaining relatively stable in many parts of Scotland, buying a house or flat is now cheaper than renting - and it has been some time since that has been the case.

The rise in first-time buyers is also good for the property industry, which has seen a sluggish market finally start to get up off the floor. And the consequent benefits for other sectors of the economy should not be under-estimated - after all, people who buy houses have to go out and buy things to put in them.

However, there is still good reason to be cautious because the rise in first-time buyers is being driven mainly by two factors - both of which should come with a health warning.

The first is record low interest rates, frozen by the Bank of England at 0.5% until unemployment falls below 7%. This guarantee has allowed many young people to take up mortgages that would otherwise be too expensive.

The problem is that the drop in unemployment is likely to happen sooner rather than later - perhaps early this year - and that could trigger the Bank to review interest rates. Should the rate go up, first-time buyers on tight incomes could find themselves in trouble. Some may default on their mortgages.

The second factor which is driving up purchases by first-time buyers is the Government's Help to Buy scheme. In the first month of the scheme alone, 2384 people in the UK signed up and, for those buyers, Help to Buy is the difference between being able to afford a home of their own and not.

But with Help to Buy too, caution is needed. This week, Prime Minister David Cameron insisted the scheme was not artificially fuelling the housing market but the fact that half of the house purchases financed by a mortgage in 2013 were made by first-time buyers is a clue to the extent to which Help to Buy may be distorting the market. The risk of another housing bubble remains.

The longer-term danger is that Help to Buy, combined with record low interest rates, is giving first-time buyers a leg-up to homes they may not be able to afford in the future. There is nothing wrong with buyers stretching themselves to achieve the ambition of owning their own home - after all, previous generations could fulfil that ambition - but these first-time buyers may also be distracting attention away from an issue which has still not been solved: the shortage of affordable homes for young people. The Government would do well to focus some more attention on that.