Assistant Director - Decision Modelling - London

Ernst & Young Advisory Services Sdn Bhd; Greater London; Hybrid; GBP 90,000 - 130,000; Full time

Job summary

EY-Parthenon, part of EY, London, seeks a Decision Modelling Assistant Director to lead complex engagements and steer high-impact strategic and financial decisions for major corporates. You will combine deep financial modelling with commercial judgement, guiding teams and client relationships to drive value.

Role offers hybrid working with UK and international project exposure, travel flexibility, and opportunities to shape the practice and adopt AI responsibly across engagements.

Qualifications

• Deep financial modelling expertise and ability to scope, challenge and assure complex work.
• Strong commercial instinct and relationship-building to convert opportunities.
• Experience leading projects to resolve complex business problems.

Responsibilities

• Lead engagements across the full lifecycle, including scoping, design and delivery.
• Co-develop complex solutions with clients and lead senior relationships.
• Actively manage engagement quality, risk, scope and economics.

Skills

Financial modelling

Commercial acumen

Project leadership

Stakeholder management

Data analysis

Education

ACA/ACCA or finance qualification

Tools

Power BI

Power Query

VBA

Job description

Location: London

Other locations: Primary Location Only

Date: 15 Sept 2026

Requisition ID: 1744228

At EY, we’re all in to shape your future with confidence.

We’ll help you succeed in a globally connected powerhouse of diverse teams and take your career wherever you want it to go.

Join EY and help to build a better working world.

The opportunity

At EY-Parthenon, our unique combination of transformative strategy, transactions, tax and corporate finance delivers real-world value – solutions that work in practice, not just on paper. Benefiting from EY’s full spectrum of services, we’ve reimagined strategic consulting to work in a world of increasing complexity. With deep functional and sector expertise, paired with innovative AI-powered technology and an investor mindset, we partner with CEOs, boards, private equity and governments every step of the way.

Competitive business depends on intelligent, informed decisions. As part of our experienced Decision Modelling team, you will help shape complex strategic, commercial and financial decisions for major corporates, private equity firms, other investment institutions, government departments and public sector bodies. You will use financial modelling, analysis and structured problem-solving to turn complexity into clear, practical insight that clients can act on.

The breadth of our work will give you exposure to transactions, bids, financing and project finance, as well as business planning, forecasting, complex contracts and tools used for ongoing decision-making. You will work directly with clients across varied assignments, building your specialist expertise and broader commercial judgement.

As a Decision Modelling Assistant Director, you will lead complex engagements at the heart of senior client decision-making. Working with Partners and senior clients, you will define the question, shape the support needed and steer a proportionate approach through to practical delivery and outcomes. You will combine deep financial modelling expertise with commercial judgement and senior client leadership, challenging established thinking, building trusted relationships and turning opportunities into successful work.

Your key responsibilities

• Lead engagements across the full lifecycle, including scoping the work, shaping the design and directing delivery, providing appropriate challenge throughout.
• Co-develop complex solutions with clients, lead senior relationships and ensure the modelling work informs wider commercial and strategic decisions.
• Actively manage engagement quality, risk, scope and economics throughout the lifecycle.
• Identify and develop new opportunities, build relevant internal and external networks and help shape new business and offerings.
• Lead and coach engagement teams to deliver high-quality work.
• Help develop future leaders, role-model inclusive leadership behaviours, support wellbeing and contribute to career development and recruitment.
• Help shape and improve our Decision Modelling services, tools and ways of working.
• Evaluate and lead safe, effective uses of AI across projects, workflows or services, enabling teams to apply approved tools responsibly and improve productivity, quality, decision-making and client value.

Skills and attributes for success

What we look for

• Deep financial modelling expertise, including the judgement to scope, challenge and assure complex work and the ability to undertake or direct complex analysis.
• Well-developed commercial instinct, with an understanding of how organisations work and the relationship-building skills to identify and develop or convert opportunities through client, internal or external relationships.
• Experience leading projects to resolve complex or poorly defined business problems.
• The ability to build consensus with senior stakeholders, adapt your style, constructively challenge assumptions and bring fresh perspective and meaningful business insight.
• Success in structuring engagements or resolving conflicts amid competing objectives, sensitivities or risks.
• Effective management of engagement scope, resources, economics, quality and risk, with governance and clear oversight of the evidence needed to support key decisions and approvals.
• The flexibility to integrate specialist input and reconcile differing disciplines to deliver coherent client solutions.
• Effective team leadership and people development, using your interpersonal awareness and clear communication to understand individual needs, set expectations, give honest feedback and create appropriate stretch.
• A strong sense of accountability for initiatives taken on and for delivery of genuine, lasting benefit.

Ideally, you’ll also have

• ACA, ACCA or another relevant finance qualification; a numerate or analytical degree; or relevant professional experience.
• Experience using complementary tools such as Power Query, Power BI, VBA or other data and visualisation platforms to improve delivery and inform decision-making.
• Confidence working with large or less structured datasets, including source-system extracts, and guiding teams on proportionate approaches to data handling.
• Experience guiding teams or stakeholders in the responsible adoption of AI-enabled tools, including validation of outputs for accuracy, relevance and potential bias, protection of confidentiality and appropriate human review.
• Experience contributing to account, sector or proposition development beyond individual engagements.
• Depth of expertise in a specialist modelling area or industry sector, with experience applying it across engagements.

What we offer you

At EY, you will be part of a global network working on high-profile projects. The role provides opportunities to work with clients and colleagues across the UK and internationally.

You will join a collaborative team that brings together colleagues with varied professional backgrounds and experience, where people are encouraged to ask questions, contribute ideas and challenge assumptions constructively. You will contribute from the outset, broaden your experience and grow your influence as a modelling specialist whose advice clients trust. The role gives you the opportunity to:

• Lead complex, high-profile work across transactions, financing, business planning and other significant commercial and strategic decisions, helping senior clients navigate complexity and move forward with confidence.
• Build your profile and reputation as an adviser clients can trust, deepen senior relationships and grow the business through new opportunities and commercial propositions.
• Influence the future of our Decision Modelling services, tools, technology and ways of working, bringing your experience and ideas to the continued development of the practice.

We work as a national team, with most colleagues based in London and a smaller team in Edinburgh. We welcome applicants from across the UK and overseas.

The role requires UK travel and occasional international travel, depending on client needs and business priorities. EY supports hybrid and flexible working and provides reasonable adjustments throughout recruitment and employment where required.

We will fuel your ambition and potential with future-focused skills development that equips you with state-of-the-art methodologies and technology-enabled solutions. With more than 25,000 people in 150 countries, you will join an inclusive and empowering culture that values your uniqueness, prioritizes your wellbeing, and immerses you in the diverse thinking and cross-cultural experiences necessary to help deliver impact to clients across the globe and to help build a better working world. Learn more about careers at EY-Parthenon.

Are you ready to shape your future with confidence?

EY | Building a better working world

EY is building a better working world by creating new value for clients, people, society and the planet, while building trust in capital markets.

Enabled by data, AI and advanced technology, EY teams help clients shape the future with confidence and develop answers for the most pressing issues of today and tomorrow.

EY teams work across a full spectrum of services in assurance, consulting, tax, strategy and transactions. Fueled by sector insights, a globally connected, multi-disciplinary network and diverse ecosystem partners, EY teams can provide services in more than 150 countries and territories.

EY refers to the global organization, and may refer to one or more, of the member firms of Ernst & Young Global Limited, each of which is a separate legal entity. Ernst & Young Global Limited, a UK company limited by guarantee, does not provide services to clients.