Nick Clegg's main problem at his first autumn conference as party leader is simply being noticed and listened to, amid all the noise of the Labour leadership storm. The latest Populus poll for The Times shows that the public likes the image of the Liberal Democrats, but does not take their policies very seriously.

There is no shortage of detailed and often controversial policy ideas - as we will see in this afternoon's debate on taxes and spending, but these do not impact on voters because the Lib Dems are not regarded as contenders for power.

Hence the single most important finding in the Populus poll is that nearly two thirds of the public (65 per cent) say: “It doesn't make any difference what policies the Lib Dems put forward because they have no realistic chance of ever putting them into practice, so ultimately they'll always be just a protest vote party at national level.” That view is taken by as many as 37 per cent of Lib Dem supporters.

By contrast only 32 per cent of voters agree that, if the party puts forward “really strong distinctive policies on important issues, it will have a chance of making a big advance by gaining more MPs at the next election, because neither of the other parties is particularly appealing to most people”.

A plus point for Mr Clegg is that the party's image has improved over the past year after slipping previously. On five out of eight measures of the main characteristics of parties, the Lib Dems are now regarded more favourably than either Labour or the Conservatives, particularly on being in touch with ordinary people. For instance, there has been a 15-point jump over the past year to 63 per cent in the number saying the Lib Dems are “for ordinary people, not just the best off”.

The party is trying to convey this message with its new redistributive tax proposals. This compares with 48 per cent for Labour and 37 per cent for the Tories.

Similarly the Lib Dems are way ahead on caring about the problems faced by ordinary people (61 per cent, up 13 points over the past year), understanding the way people live their lives (51 per cent, up 11 points), and being honest and principled (59 per cent, up 13 points). The party is just ahead on “shares my values” at 44 per cent, up 3 points. But it is in second place on having a good team of leaders (at 34 per cent, up 3 points, compared with 49 per cent for the Tories); on being competent and capable (on 37 per cent, up one point, against 53 per cent for the Tories); and being a united party (on 50 per cent, plus two points).

By contrast, twice as many voters believe the Tories are united than last year (at 60 per cent, against 30 per cent), with the Labour rating plunging from 53 to 23 per cent.

But the Lib Dems have not been able to translate this favourable image into a belief that they have the best policies on key issues. The party is only ahead on tackling climate change, at 31 per cent, against 23 per cent for the Tories. In most areas the party lags well behind both the Tories and Labour.

The Lib Dems as a party, as opposed to leading spokesmen such as Vince Cable, are simply not seen as influential on many issues. Apart from the environment, the Lib Dems' best ratings are on tackling the shortage of affordable housing (20 per cent) and getting the balance right between taxes and public spending (19 per cent).

The poll shows the difficulty for a third party to achieve a high public profile on policies. Mr Clegg, for example, is having to manoeuvre between trying to win Labour seats while defending against Tory gains.

The poll was carried out on September 5 to 7. For more details see www.populus.co.uk

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