Okie dokie, it wasn't the Great Freeze, folks. Well, not just that. Stop googling "1709 crisis" because the answer isn't there. Additionally, the Bank of England has forecast the worst slump since 1706, yet the freeze hadn't happened yet, so what gives?

At the start of the 18th century in 1702, Queen Anne's War, the second French and Indian War (and a smaller portion of the War of Spanish Succession), broke out in the colonies of North America. It had come on the heels of the ending of King William's War in 1699, the first The French and Indian War (and also part of a larger European war, The War of the Grand Alliance). Spaniards in Florida and French/Indians in Alabama were fighting the British in South Carolina. Two big results here are a) the creation of a southern English buffer zone by James Oglethorpe we call Georgia in 1733, and b) the decimation of Florida's Seminole tribes (Correction: Apalachee) . The French/Indians in Acadia (Nova Scotia) were fighting British south of the Kennebec River in New England. Big takeaway? Eventually Acadia would fall during the war in 1710, becoming the English colony Nova Scotia in 1713 (along with Newfoundland and Hudson Bay as spoils of war - Port Royal had already been taken in King William's War).

Times were tough everywhere under the Empire. William Penn was considering giving Pennsylvania back to the crown; it was broke. There were trade restrictions from one colony to another, some products banned to be exported/imported. There had been a series of droughts and crop production had dropped as a result. One prominant colonist said he had "not money, nor corn" with which to pay his debts. Added to this, well over 100 British merchant ships had been impounded attempting to trade within/between the colonies, Caribbean, and England. Spanish colonies stopped trading with British ones (much of that resumed in 1704/1705, though). Expenses were up and production was down across the Empire.

Meanwhile, the protestant dissenters were being purged in England. Marlboroughs army marched, and required funding. The Scots were being threatened by the Crown for not increasing taxes, as demanded to fund the wars, leading to the Act of Union in 1707.

By the time the European theatre Battle of Ramillies happened in May of 1706, Britian was decimated by years of expensive wars. They saw a national production output drop by 15%. That's huge, particularly for an agrarian culture still decades away from the benefits of the Industrial Revolution.

Fast forward to 1709. The mini-era geological name assigned to a span from the 1600s to the 1800s is the "Little Ice Age," and for good reason. It was cold. One year in London it reached 10°F (something-something Celcius). In the winter of 1708-1709, they had what had come to be known as a "Great Freeze." These happened often enough throughout the Lil' Ice Age (as he likes to be called). The worst wasn't even 1709, it was in the 1680s. Thats when Londoners realized London Bridge allowed ice to build up and the river would freeze solid. This started the Frozen River Thames Fairs, which continued off and on until January of 1815. While the Lil' Ice Age didnt finish for another few decades, the replacement of the old bridge in the 1830s garaunteed no more ice build ups, forever ending ice skating rinks on the Thames.

With all this freezing, trade and commerce took an additional hit, dropping production ANOTHER 14-15%.

England today is anticipating a 14%+ drop, meaning we have to look to the economic and political crisis of the early 1700s or additional impact caused by the Great Freeze to find a comperable English reduction in production.

Takeaway? It was very bad way before the cold winter of 1708/09 arrived.

E: correction by u/Somecrazynerd - According to earth science folks, the Lil' Ice Age was from the early 1300s until the mid 1800s.