I would think it would depend on HOW Britian don't get it.
If it's because "Britain don't have legally it, because no treaty of Utrecht", well...Britiain would have it de facto, by piracy (crushing spanish ships) and simple numerical advantage on sea.
If it's because "Britain is less powerful than OTL, and have a less important navy"...All the consequences depends on how much it's different from OTL, and when is the POD.