[B]• Short answer:[/B]
Just use 10 pm London time (which is 5 pm New York time) as the start of each trading day, and forget about EST/EDT/GMT/BST.
[B]• Long answer:[/B]
This is easy to sort out.
For a moment, let’s ignore Daylight Saving Time (what you call Summer Time).
If you agree that B[/B] on most trading days, forex trading volume drops almost to zero shortly after 5 pm New York time, and B[/B] this lull in trading is tantamount to the “close” of the trading day — then, the only thing you need to know is this: When it’s 5 pm in New York, what time is it in your time zone?
London (and all of the U.K.) is 5 hours ahead of New York. So, 5 pm in New York is 10 pm in London — [I]almost[/I] every day of the year.
Why not [I]every[/I] day of the year?
Well, now we have to throw Daylight Saving Time into the mix. In the summer, the U.S. and the U.K. go onto DST (or BST, as you call it). That means that the 5-hour time difference between London and New York is preserved. But, our two countries don’t shift from standard time to daylight saving time [I]on the same date.[/I]
The U.S. always makes the shift first in the spring, and last in the fall — out of synch with the U.K. and all of Europe — and it’s been this way for several years now. The result is that for 2 or 3 weeks in the spring, the U.S. has gone onto DST, while the U.K. remains on standard time. And then, for one week in the fall, the U.K. has returned to standard time, while the U.S. remains on DST.
During these periods — 2-3 weeks in the spring, and one week in the fall — the time difference between London and New York is [I]4 hours,[/I] instead of the normal 5 hours.
So, if you use 10 pm London time as the proper close of the forex trading day, then your Daily Pivots will effectively be based on the 5 pm New York close — except for 2 or 3 weeks in the spring, when you are actually using 6 pm New York time, and then for one week in the fall, when you are actually using 4 pm New York time.
Will it matter to your Pivot analysis to be off by one hour for these short periods?
It might matter, once in a while. But, if you really hate time zones and time changes, then just ignore those 2 short periods. Just use 10 pm London time (as equivalent to 5 pm New York time) throughout the year.
On the other hand, if you want to learn more about these daylight saving time shifts, THIS THREAD details all the changes which have just taken place this spring.