18. Trade and other receivables

GroupCompany
2016
£000
*Restated
2015
£000
2016
£000
2015
£000
Trade receivables46,78748,484
Less: provision for impairment of trade receivables(1,601)(1,517)
Trade receivables — net45,18646,967
Amounts receivable from Group undertakings8,4172,312
Contingent consideration2,547
Other receivables3,6592,62155
Other taxation1,9264,1881,092
Prepayments and accrued income3,8614,8695519
54,63261,1928,5273,423
Due after more than one year:1,059
Due within one year54,63260,1338,5273,423

* Restated (see note 28)

The maximum exposure to credit risk at the reporting date is the carrying value of each class of receivable mentioned above. The Group does not hold any collateral as security.

Amounts receivable from Group undertakings include amounts denominated in US dollars and include short-term loans on which interest is charged at rates linked to LIBOR.

As at 30 April 2016, trade receivables of £5,215,000 (2015: £6,969,000) were past due.

Contingent consideration that arose on the disposal of King Systems was fully written down during the year (see note 26).

The ageing of overdue receivables is as follows:

Group
2016
£000
*Restated
2015
£000
Up to 3 months4,3485,579
3 to 6 months140628
Over 6 months727762
5,2156,969

The ageing of impaired receivables is as follows:

Group
2016
£000
*Restated
2015
£000
Up to 3 months46414
3 to 6 months161
Over 6 months9761,503
1,6011,517

The credit quality of receivables that are neither past due nor impaired is considered to be good.

There are no receivables that would otherwise have been past due or impaired had their terms not been renegotiated (2015: £nil).

The carrying amount of the Group's trade and other receivables is denominated in the following currencies:

Group
2016
£000
*Restated
2015
£000
Sterling27,12825,876
US dollars2,0742,607
Euro17,25518,945
Yen1,9511,949
Swiss francs437211
48,84549,588

Movements on the Group provision for impairment of trade receivables are as follows:

Group
2016
£000
*Restated
2015
£000
At 1 May (*restated)1,51750
Acquisition of subsidiary1,288
Provision for impairment of receivables837215
Receivables written off in the period(771)(36)
Exchange movement18
At 30 April1,6011,517

Amounts are written off when there is no expectation of recovering additional cash. The other classes within trade and other receivables do not contain impaired assets.

* Restated (see note 28)