Website Migration SEO Agency London: Save Your Rankings in 2026
25 August 2026
Protect your organic rankings during a site migration. Get London SEO agency advice on URL mapping, redirects, Core Web Vitals and technical audits.
Why Website Migrations Go Wrong in London
Thousands of UK businesses lose up to 40% of their organic traffic after migrating a website. The culprit is rarely a technical platform error – it's poor SEO planning. London's competitive markets, from finance to legal and e-commerce, mean even a 2% ranking dip can cost hundreds of leads per month. Common mistakes include migrating URLs without a 301 map, changing page content during the move, forgetting to resubmit the XML sitemap, and ignoring server response times. Google's Core Web Vitals also punish sites that go live with unoptimised images or layout shifts. A London SEO agency specialises in reducing these risks. They perform a pre-migration audit, check robots.txt rules, verify GSC (Google Search Console) ownership, and create a detailed test plan. Without this forensic approach, you're gambling your revenue on a 'hopeful' migration – and in 2026, Google's AI-driven crawler notices every inconsistency.
What a London SEO Agency Does During a Migration
An expert SEO migration agency in London follows a structured process. First, they crawl your existing site and export every URL with its meta data, backlinks, and search intent. Next, they build a URL mapping spreadsheet – each old URL must map to a new one, even if the new site has fewer pages. Then comes the technical setup: 301 redirects, canonical tags, and updated internal links. The agency also handles staging environment checks: they block staging with noindex or password protection, then verify that the new site's robots.txt, hreflang, and structured data are correct. On launch day, they monitor crawl behaviour in GSC, log file analysis, and Bing Webmaster Tools. They also update Google Business Profile and any legacy citations. For London companies with multiple locations, they ensure local landing pages are preserved. Crucially, they don't just 'optimise' – they run a regression testing cycle, comparing pre- and post-migration rankings for priority keywords, and fix issues within 48 hours.
Redesign vs Site Move: Different Migration Types
Not all migrations are equal. London agencies typically handle four types: domain migrations (e.g., from .co.uk to .com), platform migrations (Shopify to Magento, WordPress to headless CMS), protocol changes (HTTP to HTTPS, or HTTP/2 to HTTP/3), and full redesigns. A redesign is often the trickiest because the visual update tempts teams to rewrite content and change user journeys. A good SEO agency will tell you to change your design OR your content – never both at the same time. Also important are micro-migrations: merging multiple subdomains into one root domain, or moving to an AI-powered site search. Each requires a different level of redirect granularity. For example, moving from a PHP CMS to Jamstack demands that you handle client-side rendering carefully or Google may see an empty page. London agencies charge by discovery and mapping effort, not just hours, because a botched migration could take months to recover.
How to Choose a Migration-Specialist SEO Agency in London
When hiring a website migration SEO agency in London, ask about their case studies. Do they have examples of moving complex e-commerce sites with 10,000+ SKUs? What tools do they use – Screaming Frog, Sitebulb, DeepCrawl, or their own in-house crawler? A credible agency will offer a pre-migration audit as a standalone project, typically costing £500–£2,500 depending on site size. Ongoing migration support is usually billed at £150–£250 per hour, or a fixed retainer of £1,500–£5,000 per month. Avoid agencies that guarantee 'zero traffic loss' – no one can promise that. Instead, look for one that provides a risk assessment, a rollback plan, and a communication SLA. London businesses should also confirm that the agency has experience with UK-specific issues: cookie consent banners affecting crawlability, GDPR data retention, and the ICO's clear guidelines on tracking. A specialist will insist on a dev server protected by IP whitelisting, not basic password auth.
The First 30 Days After Going Live
The post-migration window is where your London SEO agency earns its keep. In the first week, they run daily crawls to detect orphan pages, soft 404s, and redirect chains. They also compare Google Search Console queries before and after – look for keywords that dropped more than 20 positions. At week two, they submit a new sitemap and request re-indexing of key pages. Backlinks are another priority: they identify links pointing to old URLs and update those from major directories or press mentions. By week three, traffic should stabilise; if not, the agency will inspect the log files for crawl frequency anomalies. Expect an initial 10–30% traffic dip for high-traffic sites, especially when changing domains. That's normal in 2026 because Google's cache refreshes slowly. A professional agency tracks week-over-week trends rather than daily noise, and they fully document everything. At day 30, you should receive a migration report showing redirect map completeness, indexation coverage, and recovery forecast.
FAQ
London agencies charge between £150 and £250 per hour for migration-specific SEO work. A small site migration (under 500 URLs) might cost £1,500–£3,000, while a large e-commerce site (10,000+ URLs) often ranges from £7,000 to £15,000. Full-service retainers for ongoing monitoring start around £1,500 per month. Always request a fixed quote based on a thorough pre-migration audit.