They are certainly right that a borderless economy could help preserve the pound, but if their aim is to defend Britain's cultural identity, they will rue the day they ever heard the word ecommerce.
National character is driven by economic barriers.
What a citizen eats, reads, drives, watches, and wears is shaped simply by what's available, and what's available is shaped by borders. Tariffs and customs sharply restrict the movement of both goods and services, so countries differ from one another in part because each population has different limits on their choices in the marketplace. Until recently, geographic borders protected local businesses from serious international competition, but cross-border commerce is changing all that. The Tories are relying on the pound's symbolism as a barrier to foreign competition. But what they don't mention is that embracing ecommerce and rejecting the euro will increase international competition faster than embracing the euro and fighting ecommerce.