Prioritize pick accuracy, order cycle time, dock-to-despatch lead times, and peak throughput. Verify WMS/OMS integrations, inventory visibility, SLAs for on‑time shipments, returns processing capacity, and contingency plans for peak events. Consider slot availability, minimum billing, and scalability for seasonal volume.

Expect shorter last‑mile runs into central London, frequent parcel carrier pickups, and efficient links to major motorways and airport gateways. This density supports more daily dispatch windows and lower per‑parcel transit costs, improving same‑day or next‑day delivery economics.

Higher property and labor costs push 3PLs toward denser slotting, automation, and value‑added services rather than large low‑cost storage. Brands should compare total cost-to-serve, not just rent: look at labor productivity, pick density, automation premiums, and off‑peak operating options to manage unit costs.

Require WMS and API integrations with your OMS, real‑time inventory feeds, shipment tracking, and exception reporting. Define SLAs for order accuracy, on‑time despatch, and returns SLA. Request regular KPIs (OTD, accuracy, dwell, claims) and audit access to validate performance.