[Robert]

Assuming your temps are accurate, you may have had a very finicky maris otter?  And you may not have stirred long enough.  I had a very high finishing gravity on a Best Bitter when I mashed around 158F and did not get a good initial stir to allow for full conversion.  But I was using a replica of an 1820’s (very undermodified) English heirloom malt.  Like Martin, I got to taste a very “worty” beer.  I will always mash that malt more carefully in the future, stirring fully and step mashing it and testing for conversion.  The next batch was really expressive and full of character, very much worth the extra care in the process.

Just commiserating, but it could be something along these lines....

Slightly off topic but I plan to try said malt .... When you say step mash, do you mean something like a Hochkurz (which I do anyway even with British pale malts, checking first wort density as I go) or do you recommend a lower temperature rest, and if so, details?

[a10t2]

First I thought it was a bad crush, but this hasn't been a problem in the past -- why now?

Who crushes your malt? Whether it's your mill or a shop's, have you checked the gap to make sure it hasn't slipped?

[ynotbrusum]

Assuming your temps are accurate, you may have had a very finicky maris otter?  And you may not have stirred long enough.  I had a very high finishing gravity on a Best Bitter when I mashed around 158F and did not get a good initial stir to allow for full conversion.  But I was using a replica of an 1820’s (very undermodified) English heirloom malt.  Like Martin, I got to taste a very “worty” beer.  I will always mash that malt more carefully in the future, stirring fully and step mashing it and testing for conversion.  The next batch was really expressive and full of character, very much worth the extra care in the process.

Just commiserating, but it could be something along these lines....

Slightly off topic but I plan to try said malt .... When you say step mash, do you mean something like a Hochkurz (which I do anyway even with British pale malts, checking first wort density as I go) or do you recommend a lower temperature rest, and if so, details?

Yes Hochkurz step mashing, including a mash out - 30/30/10 minimum in my experience with the finicky Chevalier malt. 

[Robert]

Assuming your temps are accurate, you may have had a very finicky maris otter?  And you may not have stirred long enough.  I had a very high finishing gravity on a Best Bitter when I mashed around 158F and did not get a good initial stir to allow for full conversion.  But I was using a replica of an 1820’s (very undermodified) English heirloom malt.  Like Martin, I got to taste a very “worty” beer.  I will always mash that malt more carefully in the future, stirring fully and step mashing it and testing for conversion.  The next batch was really expressive and full of character, very much worth the extra care in the process.

Just commiserating, but it could be something along these lines....

Slightly off topic but I plan to try said malt .... When you say step mash, do you mean something like a Hochkurz (which I do anyway even with British pale malts, checking first wort density as I go) or do you recommend a lower temperature rest, and if so, details?

Yes Hochkurz step mashing, including a mash out - 30/30/10 minimum in my experience with the finicky Chevalier malt.

Thanks!