Many British tech startups are understandably anxious to move across the Atlantic to attack the enormous U.S. market. But as founders plot the best way to make this trans-oceanic leap, they may want to pause and look over their shoulder first—to assess the U.S. tech companies that are moving onto their turf at the same time, and potentially stealing customers and revenue.

Indeed, the U.K. is often the first overseas stop for many fast-growing, U.S. tech companies set on expansion. (This is happening despite continuing global market volatility, which has slowed growth at many tech outfits but not fundamentally changed these dynamics.) Data from fDi Markets, a research firm that tracks cross-border investment, shows that between 2020 and 2022, the city of London attracted the highest number of foreign direct tech investments from international companies, beating other global hotspots like Singapore, Dubai and Tokyo.

Pro-business British PM Rishi Sunak, with his Stanford MBA, has been quite open about trying to entice more tech firms to put down roots in the country; he reportedly lobbied San Francisco AI unicorn OpenAI for months to open its first overseas office in the U.K., which it finally did, in June.

Britain is an easy first stop for American tech firms anxious to sell in Europe. While large markets like Germany and France are attractive, the U.K.—given its linguistic and cultural similarities with the U.S.—is often the first foreign launching point. But when U.S. companies arrive on U.K. shores, they can, in my experience, wreak havoc on their British peers: The cash-rich Americans, often backed by venture capital and, later, proceeds from an IPO, can poach talent, drive up salaries and, sometimes, drop their own product prices to win market share.

And they can throw marketing spend at local customers at an alarming rate. Examples of well-funded U.S. tech firms that have made a splash on U.K. shores include now-huge outfits like Dropbox, which started focusing on the U.K. and Europe well before its 2018 IPO, and communications tool Slack, which opened its first overseas office in Dublin and then followed with a British office in 2017. Marketing software juggernaut Hubspot announced a U.K. office in 2021 and said it would create 70 new jobs.

As an American now based in London investing in European tech companies, I’ve seen this playbook from both sides. And I have some advice for how British entrepreneurs should fight back—and, ultimately, make the trans-Atlantic journey themselves to fuel their overall growth.

First, make sure your product is best-in-class. I think another reason the U.K. has historically attracted so much interest and capital from U.S. investors is because its founders have a product-first culture. British businesses, particularly those in technology, will work hard, and early, to refine and perfect their product to drum up early sales. Look at the revolutionary technology produced by companies such as British AI pioneer DeepMind, which was acquired by Google in 2014, or U.K.-based smartphone app Swiftkey, which was scooped up by Microsoft in 2016.

Many U.S. tech firms, conversely, will start with a focus on marketing/storytelling and work on the product as they go along. I think this is partly a result of the copious amounts of venture capital historically available to many American firms, which can fuel a growth-focused strategy focused on aggressive (and expensive) sales and marketing activity. U.K. startups that initially focus on a smaller, one-country market don’t need to spend that aggressively. (In 2022, nearly half of the US$415 billion in global VC funding went to U.S. companies, according to CB Insights).

My second piece of advice: Take the time to really get a read on what is happening in your specific market in the U.S. I find British companies can often be more inward-facing, given the smaller market they’re serving in the U.K. You could also argue that the whole country has been in a fairly introspective mood since Brexit. But remember, the Americans are coming!

My advice is to spend time deeply analysing the market and your competition. Read analyst reports. Go to industry conferences. Engage personally with your competitors; actually talk to them and find out what their growth plans are. The old adage of Americans being chatty is both true and a competitive advantage–it’s surprising how much market intelligence you can stumble across if you’re willing to strike up conversation with your peers.

Third, I would advise companies to leverage their investors. If your backers are international, they should have good context on your market, given their high-level view. Bring them in and involve them in your thinking about how to protect and grow your business, both here and abroad. My firm last year led a U.S.$30 million funding round in London-based restaurant-software company Vita Mojo, for example, which was driven partly by insights gleaned from other investments we’d made previously in U.S. companies in the same general sector. These include a company that focused on online ordering and another selling software to help manage all aspects of back-end, restaurant operations, from managing inventory to tracking employees’ hours at work. This gave us a holistic view of the overall hospitality-software sector and allowed us to share that knowledge with our new U.K. investment.

British tech companies that successfully defend their business at home will be better positioned to continue their growth and, hopefully, become true international players. But tech companies can only do that from a position of strength, after aggressively defending their businesses on their home turf.