Chances are that a stranger motoring around Norfolk in search of attractive market towns would come away with a particular smile of satisfaction after visiting Holt.

The town, largely rebuilt by the Georgians after a devastating fire in 1708, is pleasing to the eye.

The large and small details which blend to create that overall impact are the subject of a new booklet, called First Impressions, to be launched later this month by the Holt Society.

Its members have identified a range of features which combine to make Holt 'Holt', including old walls and alleyways, groups of small buildings suited to independent, family-run shops, the pitch of roofs, soft apricot-red Norfolk brick and weathered flint cobblestones.

The society hopes the booklet will help residents look at their town with a fresh eye and want to preserve what makes Holt special - but it is warning that those charms are under threat.

'We are reaching a tipping point where we could start to lose Holt's identity,' said the booklet's author, Mary Alexander.

Tough economic times had contributed to a growth in the number of sandwich boards, brightly-coloured signs and posters plastered across time-weathered walls as traders touted for much-needed business.

The society fears their presence could have the opposite effect; driving away those who visit and delight in Holt because it is unspoiled.

Ms Alexander, an art and design historian, is keen that traders realise the society is on their side. 'What we are not is style police or NIMBYs, and we don't want to preserve everything in aspic,' she said.

Members were aware that small businesses were having to cope with an economic downturn plus the 'double whammy' of high rents and business rates.

'This is why the Holt Society has initiated the First Impressions campaign now – because we believe passionately that the economic success of our town depends on supporting our excellent small businesses while at the same time maintaining Holt's identity and respecting the visual environment through good design,' she added.

Adapting signs to suit Holt's environment and devising trails to tempt shoppers to explore were among creative ways which could be used to help traders.

Ms Alexander cited the example of national clothing chain Fat Face which had listened to the society's advice about scale and altered its standard brand signage for its shop in the town's 1990s development, Appleyard. Similarly, high street bank Santander had toned down its signing to blend better with another north Norfolk Georgian town, Aylsham.

The booklet is illustrated with coloured pen and ink illustrations by acclaimed artist, author and architectural enthusiast Matthew Rice who has a home in Blakeney with his wife, the potter Emma Bridgewater, and whose parents are members of the Holt Society.

Free copies will be available, between April 15 and May 14, from Holt Library, the Holt Bookshop, Holt Community Centre, the tourist information centre and other outlets in the town.

And everyone is being invited to contribute ideas for design improvements, submit photos of their favourite design details in the town and enter a competition with prizes, including a signed watercolour of Holt by local artist Dot Shreeve. Further details are available in the library. Other planned events include a summer workshop for young people interested in a career in graphic design.