Why GBP/USD ("Cable") gets its nickname
GBP/USD is one of the oldest and most actively traded currency pairs, often called "Cable" — a nod to the transatlantic telegraph cable laid in the 1850s that was originally used to transmit the exchange rate between London and New York. The nickname has stuck for well over a century, even as the way the rate is actually transmitted has changed rather a lot since then.
What actually moves GBP/USD
Bank of England policy. As with any major pair involving a central-bank-issued currency, BoE interest rate decisions are a primary driver. The Monetary Policy Committee's decisions and accompanying minutes are watched closely, and — similar to the Fed — the market reaction often depends more on how the decision compares to expectations than the decision in isolation.
UK-specific political and fiscal events. GBP/USD has a notable history of reacting sharply to UK political developments, budget announcements, and fiscal policy shifts in a way that's somewhat more pronounced than EUR/USD's relationship with Eurozone politics, given the relatively more centralized nature of UK fiscal decision-making compared to the Eurozone's multi-country structure.
US dollar strength. Since GBP/USD is, from one side, simply a dollar pair, broad dollar strength or weakness driven by Fed policy or US economic data affects this pair in much the same way it affects EUR/USD, USD/JPY, and other dollar crosses.
UK economic data. Inflation, GDP, and employment data releases from the UK provide regular scheduled volatility, with the same "surprise versus expectation" dynamic that drives most data-related currency moves.
What this means if you pay or receive in GBP/USD
Given this pair's track record of sharper event-driven moves, businesses with regular GBP/USD exposure — UK companies paying US suppliers, or US companies paying UK suppliers — may want to pay particular attention to scheduled UK political and fiscal calendar events in addition to the standard central bank and data calendar, since this pair has shown a pattern of larger reactions to UK-specific news than some other major pairs show to their respective domestic news.