In British English, with allusion to food served up on a slice of toast:
– the phrase to have someone on toast and variants mean to be in a position to deal with someone as one wishes;
– the phrase to be had on toast and variants mean to be cheated, to be swindled.

The earliest occurrence of the former phrase that I have found is from One of the Principality [note 1], the third instalment in Clear the Course! A Series of Character Sketches of Racecourse Life and Character, by Edward Spencer, published in The Sporting Times (London, England) of Saturday 10^th March 1877—in the following, the speaker is a welsher, i.e., a bookmaker who disappears without trace after taking money for a bet:

Give me a good old farmer—a fat ’un—that’s the man for my bit of stuff! Let’s see, what’s the name of that little meeting in the Midlands, where the old yokel thought he’d “got me on toast?” Ah, I forget. Never mind, the name don’t matter. Backed a horse with me, in running, he did; and, to make sure I shouldn’t slope, collared hold of the green baize as my price-card was pinned to. He was looking at his fancy horse all the time, and the poor old devil evidently thought he’d got hold of my coat! Ha, ha! Bless my life, I’d have given something to have seen his mug at the finish! But of course I was half-way to the station (the railway station I mean, not the other) by that time!

The second-earliest instance of to have someone on toast that I have found is from the reply to a sporting letter in verse written by ‘Tom’ to his “hunting friend” John Topthorn, published in The Royal Leamington Spa Courier and Warwickshire Standard (Leamington, Warwickshire, England) of Saturday 8^th June 1878:

Jack Topthorn’s Reply.
                                                         Manor Farm, June 7, 1878.

Tom, my old boy,
                                          I wish you much joy,
  Of your talent for writing a letter;
’Twas capital time, and most laughable rhyme,
  In fact, you ne’er wrote me a better.

I am no poet, and right well you know it.
  Then you are such a terrible quiz:
I know you will grin at the fix I am in—
  I can fancy I see your old phiz.

I once loved the sport, as ev’ry man ought;
  But now, Tom, as I am a sinner,
If truth must be told, I am getting too old,
  And would rather enjoy a good dinner:

Some four-yeer-old mutton—don’t say I’m a glutton,
  If you do, you’re a wicked old chap.
Then, instead of your sport, some ’32 port;
  And then, my boy, half-an-hour’s nap.

And yet I remember, how each November
  I looked for, and would not have missed.
But now I’m done over and laid up in clover,
  Fit only for cribbage and whist.

And yet, Tom, you know I once used to “go,”
  As straight and as plucky as most.
I am happy to tell that many a swell
  Has owned I have “had him on toast.”

On that little bay mare, they had to take care,
  If they followed us all the day through.
With “eleven stone eight” she was safe at a gate,
  Though she only stood “fourteen-two.”

The phrase to be had on toast is first recorded in The St. James’s Gazette (London, England) of Saturday 6^th November 1886:

The judges in the High Court are always learning some new thing. Yesterday it was entered on the record that the court took judicial cognizance of a quaint and pleasing modern phrase. They discovered what it was to be “had on toast.” It was the proprietor of one of the most popular and agreeable hostelries in the Home Counties who was subjected to the process. He has been in the army; he is an innkeeper, a farmer, and a sportsman. Natheless he gave £255 for an animal described as “one of the greatest horses in England.” It could jump anything, walk five and-a-half miles an hour, and was (of course) “as comfortable as an arm-chair.” When the purchaser’s faithful ostler saw that horse he made the remark about toast. For it turned out that the greatest horse in England had bog-spavins [note 2] and a curb in one hock, and the highest price that could be got for him at Tattersall’s [note 3] was £48 6s., at which price his former owner bought him back. “Such dangers do environ” those that buy horses; in which agreeable pursuit the very wiliest are occasionally “had on toast.”

 

cf. also:
– origin of the phrase ‘as warm as toast’
– meaning and origin of the phrase ‘the toast of the town’
– meaning and origin of ‘milquetoast’
– ‘here’s looking at you’ (used as a toast in drinking)
– the cultural background to ‘Welsh rabbit’

 

Notes

 

1 Here, the Principality designates the welshers as a whole; it alludes to the Principality as a familiar designation of Wales. The verb welsh, meaning to renege on payment of money owed to a person as winnings on a bet, seems to be from the adjective Welsh, on account of alleged dishonesty of Welsh people.

2 The term bog spavin denotes a soft swelling of the joint capsule of the hock of horses.

3 Tattersall’s is an English firm of horse auctioneers founded in 1776 by the horseman Richard Tattersall (1724–95).