When Oliver asked for more, was it the later mentioned Mr. Slout the workhouse master who he asked?

I see no evidence of the Master being named.

The evening arrived; the boys took their places. The master, in his cook’s uniform, stationed himself at the copper; his pauper assistants ranged themselves behind him; the gruel was served out; and a long grace was said over the short commons.

The master was a fat, healthy man; but he turned very pale.

We are told, however, that Slout is the master of the workhouse on pg. 309.

‘You know that Mr. Slout is worse to-night, my fascinator?’

‘Yes,’ replied Mrs. Corney, bashfully.

‘He can’t live a week, the doctor says,’ pursued Mr. Bumble. ‘He is the master of this establishment; his death will cause a vacancy; that vacancy must be filled up.