Yes; this is why I record all audio – except local flights where I am just talking to Shoreham.
This is digressing but there doesn’t appear to be an automatic mp3 recorder which simply creates a file for the time it was powered up. I might knock one up 
Peter wrote:
That’s fine if you record the audio, because the CAA will not give you access to the ATC audio unless you go to a court.
OK but that issue would apply to all clearances and ATC instructions so with that assumption/issue I shouldn’t be flying in any controlled airspace or even entering any ATZ at all…
It’s plain CAS bust like it no matter how you look at it, ATC need to give you a “Radar Control Service” as you re-enter CAS, if you leave CAS on freecall enroute & 7000/2000 on txp you are “No Service” (LTC don’t give “Basic Service” OCAS) and more likely as non-identified traffic on screen and you WILL get flagged by CAIT, then the controller have to do something about it: these days this means MOR
If you stay on squawk & frequency, it still a CAS bust but nothing will happen as far as CAIT/MOR are concerned: unless ATC have a real problem with you entering again, it’s highly unlikely to will hear anything from then as 1/ it’s unlikely they will notice or 2/ you tell them and they will say OK or 3/ they accommodate low ROD that even a re-entry in airspace will not result in any loss of IFR/IFR separation, given it’s a lot of paperwork for nothing ATC will pretend it never happened, however, if you level up or climbed, it’s a different story especially if number 2 is coming behind…
If you are going in/out of CAS on climbs (low performance C172 ) or while being vectored out laterally, you still get that formal process “leave CAS in 1min BS”, “entering CAS in 1min RCS”, we even heard it once just about as the propeller & the tail gets in/out during a straight & level turn
That’s fine if you record the audio, because the CAA will not give you access to the ATC audio unless you go to a court. Pre-court, you get busted, license potentially suspended (they call it “provisionally”, to sidestep appeal routes, but it can be permanent) and you have no way to defend yourself. The court case will take 6-12 months and cost you 4-5 digits. But in a case such as this it will never get to a court, so you get all the consequences (even a warning letter is a black mark, with gasco next time) and with no defence.
In these situations I normally just ask the controller giving me the leave CAS by descent clearance whether he/she any issues if I were to re-enter CAS during descent and I never got that refused. I do that also when temporarily dropping out of CAS around Oxford and wanting to re-enter CAS around KENET/CPT, never got a refusal despite that area being busy with Heathrow westbound departures. That way I have the assurance/insurance of having obtained controller non-objection on record.
You can set 7000 on CAS boundary, not before but later on one can flip from 7000 they were instructed to use to 2000/5050 without asking anyone? why putting back your FPL sqwaks for IFR OCAS is problematic?
I really think no one give a cent or mind and it’s unlikely to cause any harm as long as you remain outside controlled airspace, anyway, one will always be busy flying single pilot IFR in IMC after getting dumped OCAS trying to avoid airspace, terrain, traffic…surely setting 7000 in the box is very down the list of priorities, one can always do it when they have runway in sight while on final or bellow radar altitude…
Any reasons why one can’t keep his airways code on descent?
If instructed to set 7000 then No, but if you “forget” to set 7000 they can’t do very much since you will have changed frequency 
Actually I have genuinely forgotten to set 7000 quite a few times…
Yes that is probably a good tactic.
Does it also work for nipping polish military airspace on descent
Any reasons why one can’t keep his airways code on descent? I keep mine until circuit or engine is shutdown, unless when I get to talk to Southend or Thames, I don’t recall anyone have complained about this?
I gave up on calling LARS or FIS for the last 20nm under LTMA, it’s just too distracting with zero operational benefit
While I am not sure on the legalities, it happens over here all the time – on every descent from above FL95 one ends up clipping the edges of the TMA reverse wedding cake, unless one opts for a steep descent (within or outside of controlled airspace). I’ll ask how it works from the controller’s POV next time I run into one.
No reference but when CAIT was introduced it used to filter out some codes (7010 was one that my old club used for tugging gliders in CTR without Class D clearance but has changed later on to some code in BGA/NATS letter of agreement), the 10s-15s, I read that in some technical paper but I am lazy to fetch it up…
