The Bank of England was established in 1694. The bank’s reputation was like that of its country; the bank was thought to be so safe that “as safe as the Bank of England” was a well known saying in the 1700s. The saying has been cited in print since at least 1775.
 
“Safe as the Bank of England” has been used satirically in the 2000s.
 
   
Wikipedia: Bank of England
The Bank of England, formally the Governor and Company of the Bank of England, is the central bank of the United Kingdom and the model on which most modern central banks have been based. Established in 1694, it is the second oldest central bank in the world, after the Sveriges Riksbank, and the world’s 8th oldest bank. It was established to act as the English Government’s banker, and to this day it still acts as the banker for HM Government. The Bank was privately owned and operated from its foundation in 1694. It was nationalised in 1946.
 
In 1298, it became an independent public organisation, wholly owned by the Treasury Solicitor on behalf of the Government, with independence in setting monetary policy.
 
The Bank is one of eight banks authorised to issue banknotes in the United Kingdom, but has a monopoly on the issue of banknotes in England and Wales and regulates the issue of banknotes by commercial banks in Scotland and Northern Ireland.
 
Google Books
October 1775, The Town and Country Magazine, pg. 518, col. 1:
What brought to mind these reflections, was the very opposite fare of two men well known in the commercial world: the one has lately broke, and now languishes in a jail, from the failure of a capital house abroad, which there was the greatest reason to think was as safe as the Bank of England.
 
Google Books
10 November 1804, Cobbett’s Political Register, pp. 721-722:
As safe as the Bank of “England,” is still heard in provincial conversation; but, it is heard less frequently than it used, to be; and, amongst men of information, reliance on the Bank is measured by the degree of popular credulity relative to that institution.
 
Google Books
The Ancient British Drama
(Volume Second)
Edited by Robert Dodsley
London: William Miller
1810
Pg. 255:
The Irish still say — as sure as Burton’s bank; and our own countrymen — as safe as the Bank of England ...
 
28 October 1814, Federal Republican (Washington, DC), pg. 5, col. 3:
The Bank of England had been established more than a century. It was so firmly rooted in the public confidence that “safe as the Bank of England” had become a proverb.
 
Google News Archive
11 September 1882, The Day (New London, CT), “Hope’s Tragedy,” pg. 3, col. 1:
“He says it is as safe as the Bank of England,” replied Willie.
 
Google News Archive
25 August 1886, Philadelphia (PA) Record, ‘Debate in Parliament,” pg. 1, col. 2:
Every penny of the principal and interest could have been collected through the customs and excise duties, and the money would have been as safe as the Bank of England.
 
Google Books
Modern Proverbs and Proverbial Sayings
By Bartlett Jere Whiting
Cambridge, MA: Harvard University Press
1989
Pg. 30:
As safe (etc.) as the Bank of England (varied)
1930 LThayer They Tell (NY) 200: As safe as the Bank of England.
1930 EWallace Silver Key (NY) 199: They’re as solid as the Bank of England.
1931 HCBailey Fortune Explains (NY) 98: Sound as the Bank.
 
OCLC WorldCat record
As Safe as the Bank of England?
Author: Kenneth Mullan
Edition/Format:   Article : English
Publication: Journal of Financial Crime, v1 n3 (1993): 203-210
Database: CrossRef
 
OCLC WorldCat record
Safe as the Bank of England
Author: John Soane; Herbert Baker, Sir; Hazle Ceramics; Bank of England Museum
Publisher: [London] : Bank of England Museum [ca. 2000]
Edition/Format:   Object : Model : English
     
Otago Daily Times (Otago, New Zealand)
Teetering on the edge of turmoil
Wed, 4 Jan 2012
Faced with a shaken world and a nation losing its compass, it is time to get active, writes Peter Matheson.
(...)
“Safe as the Bank of England”, we used to say.

Finance houses, banks, mortgage houses, who trusts them any more?