The term senior civil servents as used in the extract refers to civil servents which have served in the service for a while and have a more senior posistion in the organisation and work closly with ministers senior civil servents are crucial in the civil service as they already have politcal experience and are good judges of public opinion and policy. This experinace is crucial as the minister they serve under may have not held that posistion before so they may rely on them to formulate decsions on there behalf.
civil servents may appear cautious as they will not wish to upset the ministers they serve as ultimatly they are employed by them so it is not surprising they appear cautious. Civil servents may also appear cautious as a fith of there time is spent (as mentioned in the extract) on work directly relating to parliament ie drawing up speeches legislation responces to questions which is ultimatly very sensitive work relating directly to the posistion of the minister so they will be cautious in what the say and write.
the posistion of prime minister firstly has no constitutionally enshriened role and therefore there is no guidebook or set of rules on how he or she is to operate there government so therefore the posistion of the prime minster or the pm is largely relient on what the holder chooses it to be and what they make of it.
There are usally two main types of prime minister the presidental model and the prime minsterial model. Firstly the prime ministerial model is more cabinet focused this is usally beacause the pm has a small majority so it is neccesary for him to constsntly consult the cabinet on almost all issues and have a strong party consensus on the direction of government. A example of this kind of government was john majors early 90s government major only had a small majority of 18 so had to constantly consult his cabinet about everytihng to make sure he could get legislation through so a strong party direction was needed however this ultimatly led to the downfall of majors government over the issue of europe which destroyed the party and is a good example of a failing prime ministerial government.
Secondly the presidental model is when the pm hold a large majority so often has the freedom to pass through almost any legislation they wish to pass through a good example of this kind of model is tony blairs and thatchers goverments for example blair had a huge huge majority of 179 so was otfen free to pass through any legislation it wished. This ment that blair did not have to consult his party very much and adopted what was know as bilateral meetings ie casual meetings in corridors etc etc. However sometimes the presidental model fails beacause of the pm himself ie the 2005 counter terrorism bill blair attempted to indroduce was deafeated in a house of commons vote this helps support the “elastic band theory” the idea that whilst the pm may assert his authority the cabinet will eventually come round and reassert there power and this is a good example of this.
In conclusion these two types of prime minster styles help reinforce the idea that the pm is what beholder makes it as it is largely up to them how the do it and how it works.