Table:
|  |  | 2019 | 2018 |
| --- | --- | --- | --- |
|  | Notes | £ million | £ million |
| Due within one year |  |  |  |
| Trade debtors |  | 5.2 | 7.0 |
| Owed by subsidiaries |  | 13.7 | 9.6 |
| Other debtors |  | 0.2 | 0.7 |
| Prepayments |  | 0.4 | 0.6 |
| Current tax asset |  | 1.0 | 0.6 |
| Deferred tax | 13 | – | 1.3 |
| Assets recognised from costs to obtain a contract |  | 0.1 | 0.1 |
|  |  | 20.6 | 19.9 |
| Due after one year |  |  |  |
| Defined benefit pension plan surplus | 3 | 8.8 | 2.0 |
Paragraphs:
9. Debtors
The Directors consider that the carrying amount of trade and other debtors approximates their fair value.
The Company has no significant concentration of credit risk attributable to its trade debtors as the exposure is spread over a large number of customers.
Assets recognised from costs to obtain a contract relate to capitalised incremental costs to obtain a contract, being sales commissions arising on contracts with customers of more than one year in length. No assets were impaired or derecognised during the current year or prior year.
Question:
What was the change in the amount owed by subsidiaries?
Answer: 13.7-9.6 = 4.1