A number of unapproved a/c land at LHR each weekend using Tu 154 and no doubt at other UK airports breachung the noise regs.
As with many laws the UK fails to enforce them other than providing stringent conditions for UK based airlines. I was always under the impression that the noise regs were enforceable for pax commercial flts only and that a/c such as JT's 707 plus a number of private owned a/c were exempt from the requirement but discouraged where possible.