On 29 January 1713 as treaty was concluded between the queen of Great Britain and the States General of the United Netherlands to guarantee the protestant succession to the crown of Great Britain, and the barrier of the States General. The treaty was signed at Utrecht.
Article 14 is of particular interest as it details aspects of mutual defense. If the States General would require so, Great Britain would send 10,000 men to their assistance. Vice versa, the States General would furnish 6,000 men (well provided with arms) to assist the her royal majesty and successors. The treaty is, e.g., found in A Complete Collection of Treaties From 1688 to 1771, available from Google Books.
The treaty would soon become useful. During the Jacobite Rebellion of 1715, Great Britain had virtually no (trained) army and 6,000 men (in probably 11 battalions) arrived from the Republic to assist. Mostly to relieve British troops in garrisons. The same would happen in 1719, when Dutch troops would even participate in the battle of Glen Shiel.
During the War of the Austrian Succession, and Jacobite Rebellion of 1745, Dutch troops would again be shipped to England. A first batch of 6,000 would arrive already somewhere during 1743 and 1744, in lieu of the danger of French attempts to invade England. This danger lapsed by 1744.
In 1745, following outbreak of the '45' rebellion, Dutch troops would again serve on British soil. This time part of the troops originated from the Dutch garrison of Tounai (Doornik). The city had capitulated to the French in May 1745, and the troops were paroled under the condition that they would not fight the French. However, their employment in Scotland was rendered incompatible with this parole, as French troops entered Scotland in December 1745. Hence the Dutch were withdrawn again.