Visitors to the Olympic Games have not provided as great a boost to the London economy as expected so far, although the impact has been positive, according to research from Deloitte.

The firm's survey of 100 companies in London found 42% reported an increase in demand in the first week of the Games, compared with 27% who reported a decrease.

In contrast, Deloitte's earlier survey in January 2012 recorded 80% of respondents anticipating an increase during the Games period, with just 4% expecting a decrease.

Consumer businesses are the most positive about the Olympics, with 68% of respondents in the travel, hospitality and leisure industries (THL) and 59% of retailers reporting an increase in demand, compared with 18% and 32% respectively reporting a decrease.

However, these figures are also below expectations from January, when 80% of THL businesses and 84% of retailers were hopeful of an Olympic boost.

Heather Hancock, lead London 2012 partner at Deloitte, said: 'The biggest beneficiaries have been those companies who planned ahead and targeted Olympic visitors. Seventy-seven percent of retailers reported an increase in demand from new customers for example, compared with just 27% reporting an increase from existing customers.'

Figures from the British Retail Consortium show that retail sales for July were flat, despite the start of the Olympics. Sales rose just 0.1% in July, on a like-for-like basis, although online retail sales rose 15.6%, largely because poor weather meant consumers spent more time at home.

Helen Dickinson, head of retail, KPMG, said: 'Sadly July was a lacklustre month and it's doubtful this trend will change as early expectations that the Olympics will raise retailers' fortunes look to be wide of the mark. Central London's retailers are already being hit hard by shoppers actively avoiding the capital. It's likely that any blip of benefit the games bring will be short lived.'

Research from Experian suggests this situation may be changing as the Games progress. It says the number of people visiting shops was 11.7% lower on the first day of competition. Between 1 and 4 August, as Team GB's medal tally rose dramatically, the number of visitors to central London shops was down by between 2.1% and 4.5% compared with the same day a year earlier.

But on Sunday 5 August, when the women's marathon was being held in the centre of the city, footfall was up 4.5%.

Meanwhile, Deloitte's survey also found that only 8% of companies in London have refused to let staff watch the Games, while 47% have placed screens on working floors and 38% are allowing staff to stream online footage onto work computers.

Hancock said: 'The outstanding achievements of our athletes have undoubtedly resulted in a boost to the nation's feel-good factor which will permeate through to an increase in morale for employees, particularly where they have shared in the success. Along with concerted efforts to attract people to visit or stay longer in London during week two, it will be interesting to see if our survey results will be more positive post-Games.'

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