The Republic of Texas maintained legations in London and Paris. The London legation was at 4 St James Street, just about opposite St James' Palace, and is marked with a plaque today. There's a few pictures on this blogspot site.

Historically, the Republic of Texas maintained legations in London and Paris. As /u/lu619 mentioned earlier, the Texas Legation in London was previously located on Pickering Street off St. James Place while the Paris Legation was located on Place Vendome, very near to where the Ritz Hotel is today. However, the Republic of Texas never maintained an embassy with another country.

Prior to the Second World War, the diplomatic corps used a four-tier system of rank developed at the Congress of Vienna to represent bilateral relations between nations. Technically, this system still exists today although countries with normal relations between one another virtually always send ambassadors -- a diplomat of the first tier or rank -- to one another. The reason why Texas had a legation rather than an embassy is because the rank of ambassador was relatively rare in the mid-19th century and was reserved almost exclusively for relations between the great powers. Texas therefore never sent an ambassador, but certainly established diplomatic ties with London and Paris.