Boston Gas Company d/b/a National Grid D.P.U. 20-120 Attachment AG-51-12-3 Page 1 of 4 2020 Terrorism Premium Breakdown Original Details USD Currency FX Rate Reinsurance Terrorism Reinsurance USD 238,026 - Premiums Cyber Terrorism Reinsurance USD 235,903 - Terrorism Reinsurance USD 13,845 GBP 11,076 1.25 Broker Fees* Cyber Terrorism Reinsurance USD 13,845 GBP 11,076 1.25 Admin & Terrorism Reinsurance USD 13 Expenses Cyber Terrorism Reinsurance USD 13 Total Retail Premium: USD 501,645 *Broker fees allocated based on % of Reinsurance premium ceded (US: 42.6% & UK: 57.4%) Terrorism Boston Gas Company d/b/a National Grid D.P.U. 20-120 Attachment AG-51-12-3 Page 2 of 4 2020 Excess Liability Premium Breakdown 2020 Excess Liability Reinsurance Structure and Breakdown NGI USA Signed Premium USD Premium Layer Reinsurer Signed Line FX Rate Original Line % (Original Amount Details USD Currency FX Rate Currency) Reinsurance Premiums USD 3,222,088 GBP 2,577,670 1.25 G11: GBP10m xs GBP830.5m AXA XL 100.00% GBP 10,000,000 GBP 24,000 1.25 Broker Fees* USD 139,150 GBP 111,320 1.25 xs USD85m Total: 100.00% GBP 10,000,000 GBP 24,000 1.25 USD 30,000.00 Admin & Expenses USD 113,763 Chubb Bermuda Insurance Ltd 66.67% GBP 50,000,000 GBP 135,000 1.25 GL10: GBP75m xs GBP755.5m Total Premium: USD 3,475,000 American International Reinsurance Company Ltd 33.33% GBP 25,000,000 GBP 67,500 1.25 xs USD85m Total: 100.00% GBP 75,000,000 GBP 202,500 1.25 USD 253,125.00 *Broker fees allocated based on % of Reinsurance premium ceded (US: 50.6% & UK: 49.4%) Hiscox Syndicate HIS 33 33.33% GBP 10,000,000 GBP 27,000 1.25 Ascot Syndicate ASC 1414 16.67% GBP 5,000,000 GBP 13,500 1.25 GL9: GBP30m xs GBP725.5m MS Amlin Syndicate AML 2001 16.67% GBP 5,000,000 GBP 13,500 1.25 xs USD85m HDI Global SE 33.33% GBP 10,000,000 GBP 21,000 1.25 Total: 100.00% GBP 30,000,000 GBP 75,000 1.25 USD 93,750.00 Liberty Agency Ltd. 8.2988% GBP 10,000,000 GBP 27,000 1.25 Oil Casualty Insurance, Ltd 29.0456% GBP 35,000,000 GBP 94,500 1.25 Arch Reinsurance Ltd 10.3734% GBP 12,500,000 GBP 33,750 1.25 GL8: GBP120.5m xs GBP605m Endurance Specialty Insurance Ltd 4.1494% GBP 5,000,000 GBP 13,500 1.25 xs USD85m Argo Re Ltd 16.5975% GBP 20,000,000 GBP 54,000 1.25 XL Insurance Bermuda Ltd 14.9378% GBP 18,000,000 GBP 48,600 1.25 Markel Bermuda Limited 16.5975% GBP 20,000,000 GBP 54,000 1.25 Total: 100.00% GBP 120,500,000 GBP 325,350 1.25 USD 406,687.50 Great Lakes Insurance SE 28.57% GBP 20,000,000 GBP 38,400 1.25 Assicurazioni Generali S.p.A UK Branch 14.29% GBP 10,000,000 GBP 19,200 1.25 GL:7 GBP70M xs GBP535m xs Chaucer Syndicate CSL 1084 10.00% GBP 7,000,000 GBP 18,900 1.25 USD85m National Grid Insurance Company (Isle of Man) Limited 47.14% GBP 33,000,000 GBP 63,360 1.25 Total: 100.00% GBP 70,000,000 GBP 139,860 1.25 USD 174,825.00 GL6: GBP50m xs GBP485m xs Energy Insurance Mutual 100.00% GBP 50,000,000 GBP 110,760 1.25 USD85m Total: 100.00% GBP 50,000,000 GBP 110,760 1.25 USD 138,450.00 Great Lakes Insurance SE 20.0000% GBP 15,000,000 GBP 31,050 1.25 Liberty Mutual Insurance Europe SE 20.0000% GBP 15,000,000 GBP 42,000 1.25 GL5: GBP75m xs GBP410m xs QBE Europe SA/NV 48.3333% GBP 36,250,000 GBP 75,038 1.25 USD85m Assicurazioni Generali S.p.A UK Branch 10.6667% GBP 8,000,000 GBP 16,560 1.25 National Grid Insurance Company (Isle of Man) Limited 1.0000% GBP 750,000 GBP 1,553 1.25 Total: 100.00% GBP 75,000,000 GBP 166,200 1.25 USD 207,750.00 QBE Europe SA/NV 25.00% GBP 25,000,000 GBP 63,750 1.25 Chubb European Group SE 17.50% GBP 17,500,000 GBP 44,625 1.25 GL4: GBP100m xs GBP310m xs Great Lakes Insurance SE 10.00% GBP 10,000,000 GBP 25,500 1.25 USD85m Allianz Global Corporate & Speciality SE 25.00% GBP 25,000,000 GBP 63,750 1.25 Assicurazioni Generali S.p.A UK Branch 22.50% GBP 22,500,000 GBP 57,375 1.25 Total: 100.00% GBP 100,000,000 GBP 255,000 1.25 USD 318,750.00 GL3: GBP65m xs GBP245m xs HDI Global SE - UK 100.00% GBP 65,000,000 GBP 156,000 1.25 USD85m Total: 100.00% GBP 65,000,000 GBP 156,000 1.25 USD 195,000.00 Allianz Global Corporate & Speciality SE 22.50% GBP 22,500,000 GBP 80,325 1.25 Great Lakes Insurance SE 10.00% GBP 10,000,000 GBP 35,700 1.25 Assicurazioni Generali S.p.A UK Branch 12.50% GBP 12,500,000 GBP 44,625 1.25 Zurich Insurance Plc UK Branch 19.00% GBP 19,000,000 GBP 67,830 1.25 GL2: GBP100m xs GBP145m xs USD85m SCOR UK Company Limited 7.50% GBP 7,500,000 GBP 26,775 1.25 Berkley Offshore Underwriting Managers UK, Limited underwriting on behalf of W.R. 6.00% GBP 6,000,000 GBP 21,420 Berkley Europe A.G. 1.25 QBE Europe SA/NV 22.50% GBP 22,500,000 GBP 80,325 1.25 Total: 100.00% GBP 100,000,000 GBP 357,000 1.25 USD 446,250.00 Chubb European Group SE 27.7778% GBP 12,500,000 GBP 60,000 1.25 AIG UK Limited 22.2222% GBP 10,000,000 GBP 48,000 1.25 GL1b: GBP45m xs GBP100m xs Allianz Global Corporate & Speciality SE 27.7778% GBP 12,500,000 GBP 60,000 1.25 USD85m QBE Europe SA/NV 11.1111% GBP 5,000,000 GBP 24,000 1.25 Great Lakes Insurance SE 11.1111% GBP 5,000,000 GBP 24,000 1.25 Total: 100.0000% GBP 45,000,000 GBP 216,000 1.25 USD 270,000.00 AIG UK Limited 20.00% GBP 20,000,000 GBP 110,000 1.25 Allianz Global Corporate & Speciality SE 25.00% GBP 25,000,000 GBP 137,500 1.25 Assicurazioni Generali S.p.A UK Branch 10.00% GBP 10,000,000 GBP 55,000 1.25 GL1a: GBP100m xs USD85m Chubb European Group SE 35.00% GBP 35,000,000 GBP 192,500 1.25 QBE Europe SA/NV 10.00% GBP 10,000,000 GBP 55,000 1.25 Total: 100.00% GBP 100,000,000 GBP 550,000 1.25 USD 687,500.00 Total: GBP 2,577,670 1.25 USD 3,222,087.50 Excess Liability Boston Gas Company d/b/a National Grid D.P.U. 20-120 Attachment AG-51-12-3 Page 3 of 4 2020 Cyber Risks & Deductible Buydown Premium Breakdown 2020 Cyber Risks Reinsurance Structure and Breakdown Original Layer Reinsurer Signed Signed Line NGI USA Premium Details USD Currency FX Rate Line % Reinsurance Premiums Cyber Risks USD 1,417,631 AIG UK 35.2941% USD 15,000,000 USD 75,563 Cyber Risks USD 215,498 Tokio Marine HCC (Lloyds syndicate 4141 ) 23.5294% USD 10,000,000 USD 50,375 Retained Risk Premium Cyber Deductible Buydown USD 325,000 GL3 - USD42.5m xs USD182.5m Tokio Marine Kiln (Lloyds syndicate 0510 ) 35.2941% USD 15,000,000 USD 75,563 Broker Fees* Cyber Risks USD 77,188 GBP 61,750 1.25 Allianz Global Corporate & Specialty SE 5.8824% USD 2,500,000 USD 12,594 Cyber Risks USD 0 Total: 100.0000% USD 42,500,000 USD 214,094 Admin & Expenses Cyber Deductible Buydown USD 0 Nationwide (Scottsdale) 40.00% USD 10,000,000 USD 52,000 Total Retail Premium: USD 2,035,317 Starr Surplus 40.00% USD 10,000,000 USD 52,000 GL2 - USD25m xs USD157.5m Axa/XL (Indian Harbour) 20.00% USD 5,000,000 USD 26,000 *Broker fees allocated based on % of Reinsurance premium ceded (US: 65% & UK: 35%) Total: 100.00% USD 25,000,000 USD 130,000 Munich Re (Great Lakes) 38.46% USD 12,500,000 USD 89,375 Zurich 30.77% USD 10,000,000 USD 71,500 GL1 - USD32.5m xs USD125m Canopius 30.77% USD 10,000,000 USD 71,500 Total: 100.00% USD 32,500,000 USD 232,375 AEGIS Insurance Services, Inc. 64.00% USD 80,000,000 USD 668,766 Nuclear Electric Insurance Limited (NEIL) 12.00% USD 15,000,000 USD 129,299 Energy Insurance Mutual 4.00% USD 5,000,000 USD 43,098 Primary - USD125m Total: 80.00% USD 100,000,000 USD 841,163 NGI USA Retained Risk** 20.00% USD 25,000,000 USD 215,498 Total Retained Risk: 20.00% USD 25,000,000 USD 215,498 Total: USD 1,417,631.45 ** NGI USA retains 20% of the Primary USD125m layer totalling USD25m.