Lies, Damned Lies, etc.
For an educated man he misses the point somewhat. The problem with politicians and statistics goes back further than Disraeli.
For every politician that quotes statistics to support his/her argument there will be an opposing politician who quotes a conflicting set of statistics to support the opposing argument. And both sets of statistics may well be true, for certain values of truth. And therein lies the problem. As Disraeli pointed out you can make statistics say just about anything you want and if you do it right you're not really lying, you're just not necessarilly telling the whole truth.
Political interference is a fact of life in his job, simply because the government will decide what is counted and how. It's always been thus.
As an example our current government measure unemployment in a completely different way to the previous incumbents (and to be fair the tories changed the way it was measured more than once). So the opposition could, if they had any sense, have spent the last thirteen years quoting the figures measured their way. Most of the time the tory way of measuring would have given a higher figure than the nulabour way. Now both those figures would have been right, they would just be measuring different things and giving them the same headline name. Every time people read the unemployment figure in the news they don't want to hear how it's measured, only statisticians and politicians really care. So people don't nessarilly know that people being paid unemployment benefit while on part time courses or in part time (even voluntary) work are not counted as "unemployed and claiming benefit". They are not generally aware that people who are not entitled to unemployment benefit may not be included in the headline unemployment figure, whether they are working or not.
The very fact that his particular office exists is down to political interference. It matters not whether we are talking about a national statistical body or some bloke measuring KPIs in the audit department of a company that make plumbing fittings all real world statistics are subject to political (not necessarilly party political) interference.
If he can't accept that he's probably in the wrong job.