Montgomerie will be at Royal Troon, his home club, in two weeks after surviving a 12-man play-off in the qualifying competition at Sunningdale last night.
"I have got through by the back door, but I am there and it is the first decent thing that has happened to me for a while," said Montgomerie.
"I missed the US Open and I did not want to miss the British Open. It could be the last time I play an Open at Troon.
"I know every blade of grass there and I should have a realistic chance - now I am in it."
Justin Rose failed to qualify by a stroke, but there are three spots still available at this week's European Open and one at next week's Scottish Open.
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