We are seeking an experienced Senior Quantity Surveyor (freelance) to support a portfolio of major infrastructure and heavy civils projects across the Heathrow and HS2 corridor. The role will be split between head office in Uxbridge and two high-profile live sites. This is a long-term maternity cover assignment offering exposure to some of the UK’s most complex infrastructure environments. Key Responsibilities * Commercial management of two major heavy civils projects (HS2 & Heathrow works) * Full quantity surveying duties including cost control, forecasting, reporting, and valuations * Managing subcontractor accounts from procurement through to final account * Contract administration (NEC/FIDIC experience preferred) * Risk management and change control * Monthly commercial reporting to senior management * Supporting project teams with commercial strategy and cost advice * Ensuring robust financial control across multiple live sites simultaneously Required Experience * Strong background in heavy civils / major infrastructure projects * Proven experience working for Tier 1 contractors or subcontractors such as: * Murphy * Balfour Beatty * Costain Group * Skanska UK * Olive O'Connell * Strong NEC contract knowledge (essential) * Comfortable working across multiple sites and managing competing priorities * Strong commercial acumen with excellent stakeholder management skills Ideal Candidate * Senior QS or established QS ready to step into a multi-site lead role * Background in major infrastructure, utilities, rail, aviation, or highways * Confident working independently in a freelance capacity * Able to operate at both site and head office level * Strong reporting and client-facing capability