searching for historic exchange rate provider which meets this example data
You will most likely not be able to avoid some form of format conversion, regardless of which data you use since there is, afaik, no standard for this data and everyone exports it differently. One viable option would be, like you said yourself, using the free data provided by Dukascopy. Please take into consideration that those are spot currency rates and will most likely not represent the rate at which physical and business-related exchange would have happened at this time.
I used Oanda.com for Forex trading a couple years ago. I am in the US but I think it's available in the UK as well. At the time, they had no commissions and their spreads were comparable or better than other brokers. The spreads would just quite considerably when a big event like a Fed meeting or the unemployment figures come out, but I suspect that that is the same everywhere (or they have constant spreads and reject trades).  They did not push the high leverages like other brokers were at the time. I considered this to be very reputable, because though the profits to be gotten through 100:1 leverage are great advertising, the reality is that one unexpected spike and a newbie would lose a bunch of money in a margin call. "The prices quoted are for currency pairs traded on the foreign exchange market. For currencies traded on these exchanges, the exchange rates of a given currency pair are determined by the market, so supply and demand, investor confidence, etc. all play a role. EBS and Reuters are the two primary trading platforms in the foreign exchange market, and much of the data on exchange rates comes from them. Websites will usually get their data either from these sources directly or from a data provider that in turn gets it from EBS, Reuters, or another data source like Bloomberg or Haver Analytics. These data sources aren't free, however.  In the US, many contracts, transactions, etc. that involve exchange rates use the exchange rate data published by the Federal Reserve. You might see this in contracts that specify to use ""the exchange rate published by the Federal Reserve at 12 pm (noon) on date --some date--"". You can also look at the Federal Reserve Economic Data, which maintains data series of historical daily, weekly, and monthly exchange rates for major currency pairs. These data are free, although they aren't realtime. Data for each business day is mostly updated the next business day." You can view certain US economic data with FRED Graph or download the data to play with FRED download. Here is some example tax data: Central banks don't generally post exchange rates with other currencies, as they are not determined by central banks but by the currency markets. You need a source for live exchange rate data (for example www.xe.com), and you need to calculate the prices in other currencies dynamically as they are displayed -- they will be changing continually, from minute to minute. You can get this data from a variety of sources, but likely not all from 1 source.  Yahoo is a good source, as is Google, but some stock markets also give away some of this data, and there's foreign websites which provide data for foreign exchanges.    Some Googling is required, as is knowledge of web scraping (R, Python, Ruby or Perl are great tools for this...). I found the zephyr database, which does the job. Nonetheless if someone knows other (open) sources, be welcome to answer. I spoke to HMRC and they said #1 is not allowable but #2 is. They suggested using either their published exchange rates or I could use another source. I suggested the Bank of England spot rates and that was deemed reasonable and allowable. Good day! Did a little research by using oldest public company (Dutch East India Company, VOC, traded in Amsterdam Stock Exchange) as search criteria and found this lovely graph from http://www.businessinsider.com/rise-and-fall-of-united-east-india-2013-11?IR=T :  Why it is relevant? Below the image I found the source of data - Global Financial Data. I guess the answer to your question would be to go there: https://www.globalfinancialdata.com/index.html  Hope this helps and good luck in your search! "See my comment below about the official exchange rate. There is no ""official"" exchange rate to apply as far as I'm aware.   However the bank is already applying the same exchange rate you can   find in the forex markets. They are simply applying a spread (meaning   they will add some amount to the exchange rate whichever way you are   exchanging currency). You will almost certainly not find a bank that   doesn't apply a spread. Of course, their spread might be large, so   that's why it is good to compare rates. By the way, 5 GBP/month seems   reasonable for a foreign currency (or any) acct. The transaction fees   might be cheaper in a different ""package"" so check. You should consider trying PayPal. Their spread is quite small - and publicly disclosed - and their per-transaction fees are very low. Of course, this is not a bank account. But you can easily connect it to your bank account and transfer the money between accounts quickly. They also offer free foreign currency accounts that you can basically open and close in a click. Transfers are instantaneous. I am based in Germany but I haven't had a problem with clients from various English-speaking countries using PayPal. They actually seem to prefer it in many instances." There is a way I discovered of finding the current exchange rate before committing to buy, go to send payments, put in your own second email, pay 1gbp as the amount and it will give you the exchange rate and fees in your own currency, in my case euro, before you have to click on send payment I couldn't find historical data either, so I contacted Vanguard Canada and Barclays; Vanguard replied that  This index was developed for Vanguard, and thus historical information is available as of the inception of the fund. Unfortunately, that means that the only existing data on historical returns are in the link in your question. Vanguard also sent me a link to the methodology Barclay's uses when constructing this index, which you might find interesting as well.  I haven't heard from Barclays, but I presume the story is the same; even if they've been collecting data on Canadian bonds since before the inception of this index, they probably didn't aggregate it into an index before their contract with Vanguard (and if they did, it might be proprietary and not available free of charge). Robert Shiller has an on-line page with links to download some historical data that may be what you want here. Center for the Research in Security Prices would be my suggestion for another resource here. To answer your original question: There is proof out there. Here is a paper from the Federal Reserve Bank of St. Louis that might be worth a read.  It has a lot of references to other publications that might help answer your question(s) about TA.  You can probably read the whole article then research some of the other ones listed there to come up with a conclusion.  Below are some excerpts:  Abstract: This article introduces the subject of technical analysis in the foreign exchange market, with emphasis on its importance for questions of market efficiency.  “Technicians” view their craft, the study of price patterns, as exploiting traders’ psychological regularities.  The literature on technical analysis has established that simple technical trading rules on dollar exchange rates provided 15 years of positive, risk-adjusted returns during the 1970s and 80s before those returns were extinguished.  More recently, more complex and less studied rules have produced    more modest returns for a similar length of time.  Conventional explanations that rely on risk adjustment and/or central bank intervention do not plausibly justify the observed excess returns from following simple technical trading rules.  Psychological biases, however, could contribute to the profitability of these rules. We view the observed pattern of excess returns to technical trading rules as being consistent with an adaptive markets view of the world.    and  The widespread use of technical analysis in foreign exchange (and   other) markets is puzzling because it implies  that either traders are   irrationally making decisions on useless information or that past   prices contain useful  information for trading.  The latter   possibility would contradict the “efficient markets hypothesis,”   which holds that  no trading strategy should be able to generate   unusual profits on publicly available information—such as past    prices—except by bearing unusual risk. And the observed  level of   risk-adjusted profitability measures market  (in)efficiency. Therefore   much research effort has been directed toward determining whether   technical analysis is  indeed profitable or not. One of the earliest   studies, by Fama and Blume (1966), found no evidence that a particular   class of TTRs could earn abnormal profits in the stock market.   However, more recent research by Brock,  Lakonishok and LeBaron (1992)   and Sullivan, Timmermann an d White (1999) has provided contrary   evidence. And  many studies of the foreign exchange market have found   evidence that TTRs can generate persistent profits (Poole  6  (1967),   Dooley and Shafer (1984), Sweeney (1986), Levich and Thomas (1993),   Neely, Weller and Dittmar (1997),  Gençay (1999), Lee, Gleason and   Mathur (2001) and Martin (2001)). For manual conversion you can use many sites, starting from google (type 30 USD in yuan) to sites like xe.com mentioned here. For programmatic conversion, you could use Google Calculator API or many other currency exchange APIs that are available. Beware however that if you do it on the real site, the exchange rate is different from actual rates used by banks and payment processing companies - while they use market-based rates, they usually charge some premium on currency conversion, meaning that if you have something for 30 dollars, according to current rate it may bet 198 yuan, but if he uses a credit card for purchase, it may cost him, for example, 204 yuan. You should be very careful about making difference between snapshot market rates and actual rates used in specific transaction. Thank you. Added to my list. This is very very helpful. I knew about the blockchain and the currency. Unfortunately, I'm not a pedant about differentiating between them with capitalising the first letter. I do not, however, understand Ethereum very well at all. So will read up.