The BBC is well known for producing good television programmes, children's entertainment is one such area where the quality is superior to competitors. I have often said that CBeebies is worth the license fee alone, and I know that The Boy is a big fan of 95% of the shows that are aired on the channel.

He is however, a funny little bean about certain programmes. Rastamouse is one for example, says he doesn't like it and yet is captivated by the antics of Da Easy Crew. Another show which he is enthralled by, yet maintains that he doesn't want to watch is Grandpa In My Pocket.

It may seem now an odd thing to be admitting to, when this is clearly a post written to promote the programme, however I know full well that what he's referring to is the moment when Grandpa shrinks (he reacts in exactly the same way when Tree Fu Tom 'miniaturises', yet can explain intricate details about the plotlines), and this is purely because he doesn't understand the process of the shrinking.

What better way to cure that apprehension than witnessing it first hand?

And if you were invited to a studio in the heart of Tiger Bay to see the latest series being filmed, wouldn't you jump at the chance?

We certainly did!

During the Summer holidays, we visited the set of 'The Mill on the Marsh' (the new home for the Mason family) and met the cast and crew, watched an episode being filmed (with my hand firmly clamped over The Boy's mouth), tried on the shrinking cap (me, not The Boy; he was too worried that he'd shrink), played with Wulfy, discovered the editing process, and were sworn to secrecy.

For five months!

For five months I've said NOT ONE WORD. Not a word about meeting James Bolam, nothing about the two new children who have been welcomed into the family, not a smidgen of information about the amazing set has escaped these lips.

And I am rubbish at keeping secrets. This has damn-well nearly killed me.

Here are some of the wonderful secrets behind Grandpa In My Pocket series four:

We were greeted on set by the absolutely wonderful Mellie Buse, producer, writer and creator of the phenomenal series. Mellie has very kindly answered a few questions for us about the new series.

• What is new in this series of Grandpa In My Pocket?

The Mason Family has moved to a beautiful Windmill on the marshes just outside Sunnysands called The Mill on the Marsh. They run it as a little hotel. This Summer Grandpa's other grandchildren, whom we haven't previously met, have come to stay. They are Elsie and Josh and they both get let into the secret of the magic shrinking cap. Jason and Jemima are still there but they're all grown up now, and Great Aunt Loretta has moved into a converted pigsty next door. We also have three news Sunnysands residents; Mr Yomper Stomper (an obsessive rambler), a young Australian called Bob the Boat (who has a beautiful boat in the harbour called The Boomerang), and Miss Smiley's delightful niece, Jasmine.

• What is your role on the show? What does this involve?

My colleague, Jan Page and I have written and produced all five series of Grandpa. After coming up with the original concept we've developed and written 118 stories. We have cast it, supervised all areas of the show – design, music, costume etc. We have also done all the business and legal side involved in running a television show including finding the money and sorting out all the contracts. We're a "boutique" company and we're "writer led" which is fairly unusual in the UK. We operate a show-running system which means that we are on set all the time ready to make changes to the script to help the shoot and to make quick decisions. This means that you get a consistency in the whole vision of the project and it also means that you can shoot it faster if the writer/creator is on tap to make any quick edits if the day is going slowly. It is widely used in the U.S., less so in the UK but quite often it is a system embraced by children's programming.

• Are there any little secrets about life on the show that you can reveal to us?

Well there was an incredible sense of camaraderie on this shoot. We were blessed with the most amazing crew who all shared the same sense of humour. The two directors, Martin Franks and Iain McLean set the tone and there were a lot of jokes between the two of them. This rubbed off on the rest of the team. When they were both shooting in separate studios they could see one another's monitors and would occasionally write messages to one another and hold them up to the camera. Martin had a reputation of always shooting through a window (spot the shots!) and Iain seemed to get the lion's share of all the animals to shoot until Martin got the donkey. Oh yes! We had a day with a donkey on set. The donkey, in the scripts, was called Prudence but when the animal wrangler turned up it was clear to all that this was NOT a Prudence.  It was Geronimo and it had to be quite a big donkey in order for James Bolam to be able to ride it. Yes, there's a treat in store there! So we had a whopping great donkey in a very small studio. There was a lot of rewriting and reworking in order to get the show "in the can" and for days we all smelt of donkey. This is what we do for our art!

• What is the process of producing a series of Grandpa In My Pocket? (I mean the recording order, blue-screening, editing etc.).

First we shoot all the location footage. We did this in June last year during one of the rare weeks where there was no rain. This time we went to the north Norfolk coast because the Mill on the Marsh is the Mill at Cley, near Blakeney. We shot exteriors of the Mill, the Marsh, the river and shots of Campo and Mr Whoops' car, which is a new addition. The studio shoot began in July after two weeks of "get in." We shot from 8.00 a.m – 7.00 pm every day for nine full weeks.

Then we did three weeks of blue screen shooting with James Bolam to capture all the footage we needed for Grandpa when he's small. The edit was underway as soon as we began filming with a guide voice-over track and the Visual Effects department started on the compositing  and animating straight away. Once the edit is assembled, the programme goes to the Visual Effects team for them to put all their bits in: the animated Grandpa, the extended meadow and beach sets, the skies (which all needed changing because the weather in Blakeney was very grey on the location shoot).

Following this the shows come back to us for a final edit and we rewrite all the voice-overs to fit the pictures perfectly. Then the episodes go for approval to the BBC and once approved, they go to our musical arranger for him to work his magic.  I then direct the voice-overs with the two children and all the sound goes to our Dubbing Editor who adds effects, music and mixes the programme. Finally it goes to the On-Line Studio where the pictures are "graded" to make them look really zingy and any small technical problems are sorted. That's the process. It will continue until April this year when we deliver the last of the 52 to the BBC.

• Did Grandpa share his adventures with his own children when younger, or is it just a recent thing?

His Grandpa left him the shrinking cap which only works once you're a Grandpa yourself.  He will do the same we guess.  But we don't talk about that!!!

So, is The Boy still frightened of the shrinking man? Having watched the magic behind the shrinking? After seeing mummy wear the cap? Witnessing the visual effects in the studio and on the computer in the editing suite?

Not a jot!

The new series of 'Grandpa In My Pocket' starts on Monday 27th January 2014 at 5.25pm on CBeebies.

Many thanks to Mellie and all the cast and crew of Grandpa In My Pocket for making us all feel so welcome!