Former England batsman Geoffrey Boycott has suggested captain Alastair Cook will finish with 40-plus Test centuries, after the prolific left-hander became the country's greatest centurion.

Cook welcomed the 23rd ton of his career on Thursday, surpassing the 22 scored by Boycott, Kevin Pietersen, Wally Hammond and Colin Cowdrey en route to an unbeaten 136 on day two of the third Test against India in Kolkata.

"That's a terrific performance. I don't think it'll be such a big deal to him, to pass Wally, Colin, myself and Kevin. He is going to get a lot more unless he suffers some serious illness or injury," said Boycott.

"He has got a sound technique, he is the captain, so he'll automatically get picked - he'll be way up towards 40 tons by the time he is finished, high 30s maybe.

"If you think he'll be in his best years until he's about 32, that's five years. You play about 14 Tests a year so that's about another 70 Tests, and he'll probably get about 15 Test centuries in that. I think he'll be close to 40 tons by the time he's in his early 30s."

The skipper's vigil carried the tourists to an impressive 216 for one in response to the opposition's 316 all out, passing 7,000 Test runs - and the most by an English skipper in India - in the process.