FSA fines Barclays in LIBOR / EURIBOR misconduct case: does it prevent competition law fines?

I have just seen a tweet by Angus MacCulloch (@AngusMacCulloch) where he wondered whether the FSA case against Barclays for misconduct relating to the London Interbank Offered Rate (LIBOR) and the Euro Interbank Offered Rate (EURIBOR) (two key bank interest rates that influence the cost of loans and mortgages) would preclude an OFT investigation into possible cartel offences, since Barclays has been fined for conduct that involved other financial entities as well (see http://tinyurl.com/FSABarclays).
The question is highly relevant, since Barclays is said to have sought whistleblower immunity before the European Commission (as mentioned by Andrew Ward also on twitter, @ARWardMadrid), while it has settled the case with CFTC and DoJ. In general terms, the case raises (once again) the hard issue of the limits and overlaps between competition law and sectoral regulation--which remains an open issue with far reaching implications.
In general, it looks like the EU holds a very tough approach that requires the simultaneous, concurrent application of sectoral regulation and competition law, at least as long as the (dominant) undertakings retain some degree of discretion or room for maneuvre that would have allowed them to avoid a breach of competition law while competing within the limits set by the sectoral rules--as set in the field of art 102 TFEU by the 'ADSL saga' of the Court of Justice of the European Union [the next chapter to be delivered in the pending appeal C-295/12 P - Telefónica and Telefónica de España v Commission].
That is, complying with sectoral rules is not an antitrust defence if, within the same regulatory framework, the undertaking could have behaved procompetitively or, at least, could have avoided a breach of the competition law provisions of the TFEU. To be sure, this case law assumes that there is a clash between competition law goals and not sectoral regulation itself, but the understanding and strategic behaviour of (dominant) undertakings subjected to regulation--and ultimately, somehow, seems to blame undertakings under the (implicit) principle of the 'special responsibility' derived from market dominance and a more general duty to 'analyse and comply with' sectoral regulation in a procompetitive manner.
Per comparison, the US has a more lenient approach that tends to prevent overlaps and double enforcement of competition and sectoral rules, as long as undertakings meet the test set by the US Supreme Court decision in Credit Suisse v. Billing [127 S.Ct. 2383 (2007)]-- which requires a sectoral watchdog to be properly working and exercising its regulatory powers, and undertakings to behave within the limits set by sectoral regulation and the watchdog's decisions. Therefore, undertakings are 'off the hook' if their (possibly more competitive) conduct has been effectively overseen and approved by the sectoral watchdog. 
Under the US approach, it seems clear that, in a simplified manner, competition law should be adjusted (ie, reduced) when its application in regulated sectors could defeat the purpose and objectives of sectoral regulation (particularly, because it would impose a second check on market activities that were mandated by the sectoral regulator, diminishing legal certainty due to a potential squeeze between ex ante regulatory tools and ex post competition enforcement). If this is the case, then it may even be necessary to go so far as to refrain from applying competition law at all in regulated industries if the allegedly anti-competitive practices have been the object of specific regulation and effective supervision by the sectoral agency. But only in those cases.
In my opinion, regardless of the significant difference in approach at both sides of the Atlantic, there is nothing to be found in EU or US case law that suggests that there is a 'blanket competition law immunity' for market activities carried out in regulated industries. 
Hence, it is relevant to distinguish the LIBOR / EURIBOR case from existing case law in the EU and the US because the behaviour in this particular instance was in breach of sectoral regulation and, consequently, compliance with sectoral rules cannot be claimed as a defence by Barclays or other financial institutions that have similarly misconducted.
Moreover, price-fixing cartels are at the core of competition law prohibitions and fully in line with sectoral regulation, which cannot and does not require price-fixing agremeents (but, on the contrary, tends to promote competition by bridging gaps left by potential insufficiencies of 'natural' competitive pressure). Therefore, there is no potential clash between the goals of sectoral regulation and 'general' antitrust rules--and, consequently, no apparent spill-over or unintented consequences derived from the joint enforcement of both sets of rules.
The only concern that may be left to consider is the aggregate amount of the fines finally imposed, in order to deter overdeterrence and to avoid jeopardising the viability of entities already in a difficult financial situation (so that competition law fines do not require bail outs, for instance). In that regard, competition authorities (the European Commission, OFT, or others within the ECN)  should probably take into consideration the fines already paid to the financial supervision agencies, in order to adjust the level of the competition fines they intend to impose on the banks.
But, as a whole, the case seems to be sufficiently distinct from prior instances where the overlap between regulation and competition law has been analysed by the CJEU, and there seems to be no good reason to refrain from conducting full-fledged competition law investigations and, if deserved, to impose (adjusted) competition law fines.