Unable to find an effective geographic/non-08 number for this organisation, that used to be the Occupational Pensions Regulatory Authority.
Address PO Box 16314, Birmingham B23 3JP
The geog (01273 811800 [Brighton?]) & non-geog (08706063636) #s listed, before cutting you off, announce that a telephone service is no longer provided.
The only numbers found are both non-geog:
0845 600 0707 / 1011

Any assistance gratefully received :-)

Good Afternoon,

I am not sure if The Pensions Regulator (TPR) deals with just business or the general public as well, so that maybe why they only have an 0845 number.  Anyway, I took a look on the Pension Regulator website, and found their address which is in Brighton.  Napier House is the 1st part of the address.

I searched for The Pensions Regulator Napier House and just got the usual 0845 number, then tried with 01273 (the dialling code for Brighton) and got several useful results.

One lists a number of Solicitors at TPR Napier House, but ALL have the same contact number which suggests it's reception.  I would therefore suggest you try 01273 627600 and let us know how you get on.

I have not called it today, as it's a Sunday.

Evening,
Much appreciate your help, as well as going through the thought process that got you there - always useful for smarter ways of searching in future!
Will try the number you found tomorrow & let you know how it went.
Thanks again!

Update:
Tried 01273 627600, only to find it similar to 811800, in that it only has a recorded announcement directing callers to the 0845- numbers.
Also tried -648400, hoping it might be a reception/switchboard, but without luck again, this appearing to be some access number to an Avaya voice messaging system which, despite announcing assistance may be had by entering "Oh" = (unclear whether 0[zero] or O [letter O]), then informs either selection is invalid & suggests trying later before disconnecting the call...
In the end I contacted a number (-662086) found for the press office, who did arrange for someone to call me back.
Should I ever happen upon a geographic switchboard number, I'll make a point of listing it on this site, but have for now stopped looking and, given the degree of difficulty, am not optimistic of coming across one any time soon.
Once again, thanks for helping.

The 01273 627600 number says that "To reduce cost for our customer, the Pensions Regulator has changed its telephone number to an 0845 charging rate. Please redial…"

In nine weeks time, The Pensions Regulator will have to declare the 5 pence per minute Service Charge associated with calling its 0845 numbers.