Diploma Results Presentation Deck

20 Diploma PLC Half Year 2023 Results Seals % of Group revenue 34% Sector revenue mix C UK Aftermarket European OEM Australia * NA Aftermarket US OEM US MRO * Pro forma revenues adjusted for acquisitions and disposals completed during the year 24% 14% 10% 23% 16% 13% Revenue Organic growth Adjusted operating profit Adjusted operating margin H1 2023 highlights • International Seals +12% organic: ● ● - Excellent trading performance in R&G - Strong performance in water management segment in Australia • North American Seals +4% organic against strong comparator (H1 2022: +19%) Strong double-digit growth in North American Aftermarket and MRO Softer performance in US Industrial OEM this half - Portfolio development - H1 2023 £198.4m +8% £35.7m 18.0% Two bolt-ons in North American Seals Three bolt-ons in R&G H1 2022 £137.4m +15% £25.8m 18.8% Margin -80bps: Change +44% +38% -80bps R&G first year dilution R&G improving margin plus Sector scale/performance benefits see margins improve in H2 DIPLOMA PLC

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