The 1,100-pupil secondary is exactly the kind of school which the Government says its policies of monitoring and evaluation are designed to help. Located in the "least desirable" residential area of Aberdeen and the product of a bitterly contested merger, its birth in 1988 could not have been more inauspicious.
As Mr Marr put it in a talk he gave last year: "It was apparent that many pupils were poorly motivated, many having experienced failure throughout their school careers. The majority of the new school's pupils had spent their entire secondary careers with the threat of closure hanging over their heads. This threat had been equally damaging to the morale of staff and young people alike and had given messages about the quality of experiences being provided in both establishments.
"In addition many pupils tended to be dismissive of others' successes which in turn made them reluctant to achieve in case they were labelled as 'swots'. "
Exceptional action was clearly required along with exceptional leadership. Both have been provided, as an HMI report made evident in April. The school is no longer "the worst in Scotland," if this year's raw exam results are any guide; it is not even the worst in Grampian although still well below the average performance for the region's schools.
There may now be a measure of familiarity breeding contempt but Mr Marr says the school and its parents have become more relaxed and aware that exam results are only one yardstick of a school's performance - "and we treat them now with a healthy caution."
He stresses, however, that exam results cannot be discarded. "I do see exam performance as fundamentally important," he said. "What we want to do is to maximise young people's achievement in every area and that has got to include performance in national examinations."
But he believes parents can set that alongside other factors which they also regard as important, such as the atmosphere in the school and how it deals with them on a day-to-day basis. The safety of the pupils, the approachability of the staff, communications with the home and extra-curricular activities all count strongly in parents' eyes, Mr Marr adds.
But the ability of St Machar to stretch its pupils is seen as important too - and this is where real "value-added" indications can be sought in identifying the impact schools are making on the progress of their pupils. And that means all pupils. Mr Marr says one of the results that has pleased him most is the ten per cent increase in the number of youngsters this year who got Standard grade Credit and General awards, lifting them out of Foundation level. A slight increase has also been recorded for those emerging with three or more Higher passes.
As far as St Machar is concerned, Mr Marr says they now have the confidence to use the exam figures as an evaluation tool and not worry too much about what anybody else thinks of them. They set their own "value-added targets" last year and are reasonably pleased with the results.
The aim of a 15 to 20 per cent improvement against the national benchmarks (known as "national comparison factors") in the number of pupils getting three or more Standard grade Credit awards met an actual 19 per cent increase. The school also wanted a decrease in the number of Foundation awards per Standard grade pupil against the national factors, although the 11.5 per cent result was less than the 15 to 20 per cent it hoped for. There was also a notable improvement in the fifth and sixth year ratios for students gaining three or more Higher passes, up 17.4 per cent against a 20 per cent target. The fourth aim, to increase the return rate into S5, saw a ten per cent rise.
So how does a school set about acquiring what Mr Marr calls an "attainment culture?" It is partly to do with education and partly with culture and it is partly formal and partly informal, he suggests. "It means increased differentiation of pupils' work, involving individual study programmes, but also sheer dogged determination by staff in pursuing youngsters for things like folios and investigations. It's all about creating the impression that the school is a place of work where we want to ensure the pupils achieve the best they can."
Achievement, of course, takes different forms and a recurring theme with Mr Marr is the need to celebrate all these different forms. So an end of session "celebration" is organised to mark the individual and collective achievements of as many pupils as possible. But it is not just about dux medals for the academically-inclined but also recognition for the musician of the year, the pupil who has done most to overcome adversity, sporting prowess and achievements outside the school.
St Machar also took an early decision to challenge the anti-school mentality which had emerged during the locust years and deliberately opted to use the arts as the vehicle.
Time for art, music and drama was increased by five per cent to provide an integrated programme for the first and second years. This tapped into the motivational aspects of creative and aesthetic activities but also reflected a belief in the fact that, according to Mr Marr, "the arts provide a greater number of pupils with the opportunity of tasting success and receiving praise."
This clearly had dramatic effects as Mr Marr himself found when he popped into the drama studio to find a movement activity in progress involving a group of second year boys holding hands. "They were totally unabashed," he says. "Prior to this, such behaviour might have led to the appearance of unkind graffiti. "
Clearly the message from a school like St Machar Academy is that it has to advance on a broad front, from increasing the teaching time for Highers and reducing class sizes in S1 to "classroom partnerships" which allow youngsters to build up bronze, silver and gold stars that then become part of their Records of Achievement. This last initiative, says Mr Marr, is based on praise and reward which has led to more co-operation between staff and pupils. "It hasn't minimised low-level disruption but it has reduced it significantly and the result is the class gets through more work."
Work, success, praise and recognition: these appear to be the watchwords for a school that wants to think positive in order to attack under-achievement. "It's a very, very slow process," says Mr Marr, "and we are not pretending that our approach is new or superior or that other schools in similar circumstances have not achieved more - but it has certainly worked for us."