England and Wales in August

That sounds like a wonderful trip! Very nice and well-thought out itinerary, too. With regards to London, I will be taking two of my grandkids there next year (similar ages to yours, but one boy and one girl). Some of the places I was thinking of:

1. Hampton Court Palace. It's just a gorgeous place to visit and I think your boys would really enjoy it. There is so much to see and do there, and most kids absolutely love the giant maze.
2. Greenwich, which has the Cutty Sark, a restored 19th-century ship, the huge National Maritime Museum, the Royal Observatory where you can straddle the Meridian line and stand in two different time zones at the same time.
3. Are they Harry Potter fans? There are a number of places that they might enjoy, including the Warner Brothers Studio north of London.
4. Bletchley Park, if they are interested in WWII history. This is where the codebreakers worked.
5. Borough Market in South Bank is really fun and they could try some great food there, but if you're there in August, try to go early in the day as it gets very crowded around lunch and after. I was there this year in mid-March, and couldn't believe how crowded it was then.

We enjoyed Pembroke castle, Carew Castle & Tidal Mill (just walked around it), and Tenby. In St. David’s we walked a couple segments of the coastal path. Near Nevern is Pentre Ifan Burial Chamber and in Nevern is St Brynach's Church and the weeping Yew tree. The burial chamber is along a one track/lane road, but very much worth visiting.

Near Corwen is the interesting Pontcysyllte Aqueduct. There’s also Plas Newydd Historic House & Gardens, consider spending some time on Anglesey. There are a number of sights on it, from the Melin Llynon and South Stack lighthouse, to burial chambers, Beaumaris castle, and the town with the long name, Llanfair…gogogoch..

Haven’t been to it, but near Chester is The National Catholic Shrine of St Winefride..

We're also considering a day trip to Liverpool for the British Music Experience and perhaps exploring the historic walls of Chester. Any tips for these excursions?

If you go to Liverpool, try to find time to stop at the Philharmonic, a gorgeous pub with a lot of history located on Hope St. It is a very spectacular and very opulent pub, with mahogany fireplaces, and mosaic bar counters. It was really gorgeous and had a very art nouveau vibe. Your boys will enjoy the men’s toilet, which has beautiful marble urinals and inlaid mosaics. :-) The Beatles used to frequent the Philharmonic bar many decades ago. In 2018, however, James Corden and Paul McCartney filmed a Carpool Karaoke episode and at the end, they wound up in the Philharmonic with Paul performing before a very stunned crowd (the scene starts at 15:30). The episode was really moving.

Chester is well worth a visit. It is one of the most charming places I’ve been to. It’s a walled city, similar to York, and was so much fun to walk around in. Chester has an old-world charm with all the quaint buildings, and especially the black and white Tudor-style buildings. The streets are narrow and cobbled, with many running alongside canals, and are lined with shops, cafes, and pubs. It really creates a wonderful atmosphere for strolling and exploring. Chester Cathedral is worth a visit, too. I stopped at the lovely Huxleys, a cafe with a porthole that you can look out of and see a gorgeous view of the city. The pot of tea and homemade Bakewell tart were quite tasty, too. :-)

If you are near Llangollen, Wales (which you will be if you visit Corwen), I highly recommend The Corn Mill restaurant there. It was lovely and the food was very good. There are old stones on the outside of the building (it dates back to the 1700s), but it is very modern/rustic on the inside, with lots of glass and wood. It was originally a mill and there are still some features of the mill left. There are old beams everywhere, and a turning water wheel behind the bar. The decks outside sit directly above the churning river, with rapids running through, and there are gorgeous river and mountain views from the huge picture windows inside. Across the river, there is a quaint train station where steam-engine trains arrive. It's a wonderful place for a meal and the scenery is incredible.

Regarding Downham- I assume you have seen the village website- https://www.downhamvillage.org.uk/

Maybe you would like to see one or both of the movies mentioned on the website, which was filmed in the village. "Whistle down the Wind" is a very atmospheric movie, I think. It will immerse you in the area.

And for a meal you will see about the Assheton Arms.

You will also see on the website about the village banner, now at Clitheroe Castle- irrespective of that you should go to see the Castle. If it is a Market Day it is a really good example of a Lancashire Market- and you must try a Lancashire Hot Pot while there, if you find it on the market or in a pub. I always say you should have hot pot with hot red cabbage (opinions may vary on the red cabbage- if you can get the cabbage with raisins and a bit of port wine in the mixture that is heavenly to me).

On a totally different note- and it is a very acquired taste- try some tripe if you dare.

Chorley Cakes are another food you should have.

Do get up into the Forest of Bowland (which isn't a forest of trees, these days) but is stunning natural landscape (an Area of Outstanding Natural Beauty- AONB)- especially the village of Slaidburn, and the Trough of Bowland

This wikipedia article tells you all about the history of the area- https://en.wikipedia.org/wiki/Forest_of_Bowland

You should also learn about Pendle witchcraft if you want to understand the area.

Do you have an address for your gggmother, or details of tombstones at the Church which you want to see?

Sorry I know there is more than one day there.

Also Whalley Abbey

For London, you could check out some of the Museum Guide videos on YouTube. She has quite a few on all things quirky and spooky in London plus some really well done museum guides. https://youtu.be/Ka17aNKyr9c?si=c4_GFkG-lVtH7Mwb

My niece really enjoyed the food halls in Harrods and Fortnum & Mason.

If it were me I would have you staying much longer in and around Clitheroe in the Ribble Valley - but in truth many of us would say the same about our own patches of the UK.

Stuart has already given you more than a day's worth of activities but I'm going to add a few more. On your way from Manchester see if you can find time to visit the Singing Ringing Tree on the moors to the south of Burnley - https://en.wikipedia.org/wiki/Singing_Ringing_Tree,_Burnley

If you haven't booked your accommodation yet you can actually stay at the Assheton Arms now that it has re-opened. Actually the rooms are in a cottage just round the corner. https://www.jamesplaces.com/assheton-arms/

Clitheroe has a wonderful food hall as well as the market with a brewery and a huge and engaging bar next door - all in Holmes Mill -https://www.jamesplaces.com/holmes-mill/ There's also a hotel here, run by the same people as the Assheton Arms.

The Ribble Valley and the Forest of Bowland have a spectacular mix of aural landscape and beautiful villages, many of them filled with wonderful pubs. Several of the UK's best gastropubs are in the locality. For my view better than the Cotswolds with hardly any tourists - in fact many British people won't have been there.

A slight correction to Stuart's post - the Forest in the Forest of Bowland refers to its older meaning of hunting rights, rather than a collection of trees.

Near Stroud your children would enjoy Woodchester Park. It’s National Trust land (house is not owned by them and is closed) with lakes and a play trail. There is a new entrance via Tinkly Gate cafe (also NT owned) where you can park up and use the cafe and toilets.

We did South Wales and England in 2017.
I recommend in S. Wales doing St. David, Tenby and Cardiff. Cardiff Castle and other nearby castles as well as The Museum of Welsh Life.
The Cotswolds are great, in two full days you should be able to cover the wide area quite well.

If you can make to the Cardiff area, I agree that the Museum of Welsh Life is a must see. Cardiff is easily reached from London and there is a bus to the Museum.

Great suggestions, thank you everyone!

Re- Clitheroe and Downham- by chance this morning I met with someone from Clitheroe who I haven't seen for several months, and asked them the question. And we have some extra things (this is as much for anyone else reading this thread in the future)-

1- If there is a play or other event on at the Grand Theatre, go there;
2- The Ribble Valley Sculpture Trail at Brungerley Bridge, Clitheroe (near the Cemetery) and the Pendle Sculpture Trail at Barley;
3- The best of many cafes in town my contact suggests is The Blueberries Cafe at the Market (with their porridge being a real speciality- and my contact is Scottish!). But all their food is top quality and reasonably priced- a bit of a hidden Gem;
4- For excellent quality Savoury and Sweet Pies and hand made sandwiches- The Artisan Bakery - opposite Sainsbury's- especially the Steak and Ale Pie;
5- In the spring- Spring Wood for the bluebells and the daffodils;
6- Back at the Castle the photograph galleries- photographs of the local landscape and wildlife;
7- Dawson's Department Store (opposite the Railway Station) and their old fashioned Hardware Department- they have anything you could want in terms of hardware in any quantity you want. So if you want one single screw you can buy it, rather than a pack.
Every town used to have them, now they are a real rarity

Back in Downham you cannot buy a house (only rent them) or have a TV aerial- to maintain the period feeling of the village.

So that is a local's perspective on the question.

If we didn't put it above the Market happens on Tuesday, Thursday and Saturday- but places like Blueberries are open daily.