13 Trade and other receivables

The directors consider that the carrying amount of trade and other receivables approximates to their fair value.

The average credit period on revenues is 24 days (2007: 23 days). No interest is charged on the trade receivables outstanding balance. Trade receivables overdue are provided for based on estimated irrecoverable amounts.

Included in the Group’s trade receivable balance are debtors with a carrying amount of £51.2m (2007: £57.3m) which are past due at the reporting date for which the Group has not provided as there has not been a significant change in credit quality and the Group considers that the amounts are still recoverable. The average age of these receivables is 96 days (2007: 134 days).

The Group’s exposure to credit risks and impairment losses related to trade and other receivables are disclosed in note 28, Financial Instruments.

In determining the recoverability of trade receivables, the Group considers any change in the credit quality of the trade receivable from the date credit was initially granted up to the reporting date. The concentration of credit risk is limited due to the customer base being large and spread across the Group’s operating segments. Accordingly, the directors believe that there is no further credit provision required in excess of the provision for impairment losses. No collateral is held by the Group as security.

Within the provision for impairment losses there are no specific trade receivables (2007: £nil) from debtors which have been placed into liquidation or administration.

At the reporting date there were no trade and other receivables which have had renegotiated terms that would otherwise have been past due.