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investments accounted for using equity method +10% market area price change Sensitivity Analysis 10% Increase In Market Area Price Change Sensitivity Analysis 10% Increase In Market Area Price Change Current tax assets Current tax assets, current Categories of related parties [axis] Categories of related parties [axis] Reclassification adjustments on exchange differences on translation before tax, investment Reclassification Adjustments On Exchange Differences On Translation Before Tax, Investment Reclassification Adjustments On Exchange Differences On Translation Before Tax, Investment Disclosure of detailed information about borrowings [line items] Disclosure of detailed information about borrowings [line items] Income taxes paid (refund) [abstract] Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward] Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward] Changes In Fair Value Measurement, Assets (Liabilities) [Roll Forward] Total profit for the period Profit for the period Profit (loss) 10% increase in commodity prices Sensitivity Analysis 10% Increase In Commodity Prices Sensitivity Analysis 10% Increase In Commodity Prices Financial assets Financial assets Joulent LLC Joulent LLC [Member] Joulent LLC Community Offshore Wind Community Offshore Wind [Member] Community Offshore Wind Amendment flag Amendment Flag Components of equity [domain] Components of equity [domain] Major transformation programme Major transformation programme Expense of restructuring activities Changes in restrictions on asset recognised [Roll Forward] Changes in restrictions on asset recognised [Roll Forward] Changes in restrictions on asset recognised Exceptional items and remeasurements Description of accounting policy for exceptional items [text block] Total non-current liabilities Non-current liabilities Equity dividends Dividends recognised as distributions to owners Disclosure of operating segments [line items] Disclosure of operating segments [line items] Closing rate applied at period end Closing foreign exchange rate Interim dividend Interim Dividend [Member] Interim Dividend Segmental analysis Disclosure of entity's operating segments [text block] Capital commitments Capital commitments Total other revenue Other Miscellaneous Revenue, Non IFRS15 Other Miscellaneous Revenue, Non IFRS15 Retained earnings Retained earnings [member] Finance income and costs Disclosure of finance income (cost) [text block] Bank overdrafts Bank overdrafts 10% decrease in commodity prices Sensitivity Analysis 10% Decrease In Commodity Prices Sensitivity Analysis 10% Decrease In Commodity Prices Scrip dividend-related share issue Scrip Dividend-Related Share Issue Recognized As Distributions To Owners Scrip Dividend-Related Share Issue Recognized As Distributions To Owners Interest on restrictions on asset recognised Irrecoverable Surplus, Restrictions On Assets Recognized, Increase Through Interests Irrecoverable Surplus, Restrictions On Assets Recognized, Increase Through Interests Assets and liabilities not classified as held for sale [domain] Assets and liabilities not classified as held for sale [member] Scenario [Domain] Scenario [Domain] Analysis of income and expense [abstract] Analysis of income and expense [abstract] Increase (decrease) due to changes Increase (decrease) due to changes in accounting policy required by IFRSs, cumulative effect at date of initial application [member] Reclassification to held for sale Increase (Decrease) In Cash And Cash Equivalents Through Reclassification To Held For Sale And Discontinued Operations Increase (Decrease) In Cash And Cash Equivalents Through Reclassification To Held For Sale And Discontinued Operations +20 basis point increase between Retail Price Index (RPI) and Consumer Price Index (CPI) Sensitivity Analysis 20 Basis Point Change Increase In Retail Price Index And Consumer Price Index Sensitivity Analysis 20 Basis Point Change Increase In Retail Price Index And Consumer Price Index Authorised capital commitments but not contracted for Authorised capital commitments but not contracted for Impairment losses on financial assets Impairment loss recognised in profit or loss, trade receivables Disclosure Of Exceptional Items [Table] Disclosure Of Exceptional Items [Table] Disclosure Of Exceptional Items Net (losses)/gains through the consolidated income statement for the period Gains (Losses) Recognized In Profit Or Loss, Fair Value Measurement, Assets (Liabilities) Gains (Losses) Recognized In Profit Or Loss, Fair Value Measurement, Assets (Liabilities) Dividends Disclosure of dividends [text block] Net gain on investment held by NG Partners Net Gain (Loss) on Investment Held, Included Within Revenue Net Gain (Loss) on Investment Held, Included Within Revenue Derivative financial assets Current derivative financial assets Notional amount Notional amount Fair Value Measurement [Abstract] Fair Value Measurement [Abstract] Fair Value Measurement [Abstract] Net defined benefit asset Net defined benefit asset at 1 April Net defined benefit asset at 30 September Net defined benefit liability (asset) Proceeds from issue of treasury shares Proceeds from sale or issue of treasury shares Diluted earnings per share (in GBP per share) Diluted earnings (loss) per share Major transformation programme Major Transformation Programme [Member] Major Transformation Programme Funding surplus/(deficit) Funding surplus/(deficit) Surplus (deficit) in plan Pensions and other post-retirement benefit obligations Non-current provisions for employee benefits Average effective tax rate Average effective tax rate Restrictions on asset recognised Opening restrictions on asset recognised at 1 April Closing restrictions on asset recognised at 30 September Irrecoverable surplus Irrecoverable Surplus, Restrictions On Assets Recognized Irrecoverable Surplus, Restrictions On Assets Recognized At fair value At fair value [member] Number of other post-employment benefit plan Number Of Other Post-Employment Benefit Plan Number Of Other Post-Employment Benefit Plan Net assets Assets (liabilities) Schedule of basic and diluted earnings per share Earnings per share [text block] Cash outflows on derivatives Payments For Derivatives Contracts, Classified As Financing Activities Payments For Derivatives Contracts, Classified As Financing Activities Liabilities Net defined benefit liability Purchases of intangible assets Purchase of intangible assets, classified as investing activities