Landlords claim that high street shop rents have fallen by a third over the past 20 years and that they are being more flexible in the tough climate.

The British Property Federation has presented the findings of an independent retail study by the Investment Property Databank (IPD) to Mary Portas, who is currently carrying out a review of the high street for the government.

The report, which studied 47,708 retail tenancies, found the average lease length is now 5.7 years, and there has been a significant increase in break clauses as retailers seek to protect themselves against economic uncertainty. 34% of new leases for high street shops have a break clause, up from 3.9% in 1999. The average rent free period is 10 months.

Separate IPD data shows that while inflation has risen by 94% since 1989, rents for standard shops have only risen by 24%, so in real terms have therefore fallen by 37%.

Rental growth since 1989 has been up 51% in central London, and 24% across the rest of the UK. Shops will have seen their rates bill rise by 94% since 1989.

Liz Peace, chief executive of the British Property Federation, said: “The issues facing our high streets are extremely complex with recession, structural changes caused by the internet and consumer preference all in play. In such times of change it is important that leases adapt.

“Today’s data clearly shows landlords are increasingly flexible and retail property leases continue to adjust to economic conditions, with leases that are shorter, offering breaks and substantial rent-free periods to help new shops to get off the ground.

“Whilst rents in prime retail areas and sites such as shopping centres will have increased substantially, many high street shops will have rents that in real terms are substantially lower than in 1989.”

She continued: “During the last early-90s recession, there were legitimate claims from the retail community that the ‘institutional lease’, which commonly was for 20 years plus, with upward only rent reviews and no breaks, was inconsistent with many retailers’ needs. The property industry has significantly changed the variety of its offer and I don’t think that is always well recognised.

“Rather like our high streets, however, the property industry thrives on its variety, and ability to raise investment. There is no one size lease, but a mix that caters for our industry’s office, industrial and retail customers.”